Wednesday
June 19, 2013

# Homework Help: Science: Physics

physics
In the sport of skeleton a participant jumps onto a sled (known as a skeleton) and proceeds to slide down an icy track, belly down and head first. In the 2010 Winter Olympics, the track had sixteen turns and dropped 126 m in elevation from top to bottom. (a) In the absence of ...
Monday, April 15, 2013 at 3:05pm

physics
A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 74 kg, and the height of the water slide is 12.6 m. If the kinetic frictional force does -6.1 × 103 J of...
Monday, April 15, 2013 at 2:57pm

physics
A projectile of mass 0.817 kg is shot straight up with an initial speed of 25.5 m/s. (a) How high would it go if there were no air resistance? (b) If the projectile rises to a maximum height of only 9.14 m, determine the magnitude of the average force due to air resistance.
Monday, April 15, 2013 at 2:36pm

physics
the mass of the ball is 0.43kg and the weight of the player is 900N.the player is at rest.whAt is the normal force exerted on the exerted?
Monday, April 15, 2013 at 2:26pm

k
Two wires parallel to each other and seperated by a distance d carry different currents; they exert a force with magnitude F on each other. (a) The wires carry current in opposite directions. If the current carried by both wires is divided by five and the distance between the ...
Monday, April 15, 2013 at 1:44pm

physics
If only conservative forces are acting, total mechanical energy (KE + PE) is not necessarily conserved. True or False?
Monday, April 15, 2013 at 1:19pm

physics
For non-conservative forces, the work done does depend upon the path taken. True or False?
Monday, April 15, 2013 at 1:17pm

physics
The work done by non-conservative forces is equal to the total change in kinetic and potential energy. True or False?
Monday, April 15, 2013 at 1:16pm

physics
A radio station on the surface of the earth radiates an EM-wave with an average total power of 50 kilo-watts. Assuming the transmitter radiates equally in all directions (not in real life), find the amplitudes Emax and Bmax detected by a satellite at a distance of 100km from ...
Monday, April 15, 2013 at 12:59pm

Physics
An electric space heater draws 15.5 A from a 120 V source. It is operated, on the average, for 4.0 h each day. (b) How much energy in kWh does in consume in 30 days? (c) At 11 per kWh, how much does it cost to operate the heater for 30 days?
Monday, April 15, 2013 at 12:48pm

Physics
Vector A is described as having magnitude -7 and angle 30degress. Which is an equivaent statement of magnitude and angle of vector A? (Note: All angles are measured counterclockwise from x-axis.)
Monday, April 15, 2013 at 12:00pm

physics
A wagon is being pushed by a small child along a sidewalk. If the wagon has a mass of 8kg, a coefficient of friction of 0.3 and is accelerating at 0.2m/s what force is the child applying
Monday, April 15, 2013 at 10:53am

physics
A 2.4-kg cart is rolling along a frictionless, horizontal track towards a 1.3-kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts ...
Monday, April 15, 2013 at 9:22am

physics
A skier starts from rest at the top of a hill. The skier coasts down the hill and up a second hill, as the drawing illustrates. The crest of the second hill is circular, with a radius of 39.6 m. Neglect friction and air resistance. What must be the height h of the first hill ...
Monday, April 15, 2013 at 9:06am

physics
A semi-trailer is coasting downhill along a mountain highway when its brakes fail. The driver pulls onto a runaway truck ramp that is inclined at an angle of 19.0° above the horizontal. The semi-trailer coasts to a stop after traveling 170 m along the ramp. What was the ...
Monday, April 15, 2013 at 8:54am

physics
An object with a charge of +6.0 µC is 0.30 m from a second object and experiences an attractive force of 1.80 N. What is the magnitude of the charge on the second object? (µC = 1.0 × 10-6 C) (Answer: -3.0 µC) The answer is provided but I don't know ...
Monday, April 15, 2013 at 8:42am

Physics
36.​A 50.0-kg block and 100-kg block are connected by a string. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between the 50-kg block and incline is 0.250. Determine the change in the kinetic energy of the 50-kg block as it moves ...
Monday, April 15, 2013 at 7:50am

Physics
A solenoid is 3.2 m long and has 500 turns per meter. What is the cross-sectional area of this solenoid if it stores 0.32 J of energy when it carries a current of 12 A? So I used L = 2*E / I^2; and then I used A = L*l / (uo * N^2) but my answer isn't coming out right at ...
Sunday, April 14, 2013 at 10:58pm

Physics
A 100 W lamp is connected to 120 V, and its current is measured. A resistor is added to the lamp to reduce the current to half its original value. (a) What is the potential difference across the lamp? (b) How much resistance was added to the circuit? (c) How much power is now ...
Sunday, April 14, 2013 at 9:55pm

Physics
A circuit contains six 270 lamps and a 18.0 heater connected in parallel. The voltage across the circuit is 120 V. (a) What is the current in the circuit when four lamps are turned on? (b) What is the current in the circuit when all lamps are on? (c) What is the current in the...
Sunday, April 14, 2013 at 9:19pm

Physics
A transistor radio operates by means of a 9.0 V battery that supplies it with a 40 mA current. (a) If the cost of the battery is \$0.50 and it lasts for 300 h, what is the cost per kWh to operate the radio in this manner? (b) The same radio, by means of a converter, is plugged ...
Sunday, April 14, 2013 at 9:10pm

physics
The L-shaped object in the figure below consists of three masses (m1 = 8.90 kg, m2 = 1.16 kg and m3 = 2.40 kg) connected by light rods of length L1 = 1.29 m and L2 = 1.86 m.What torque must be applied to this object to give it an angular acceleration of 1.46 rad/s2 if it is ...
Sunday, April 14, 2013 at 9:08pm

physics
Car A negotiates a curve of 60 m radius at a constant speed of 50 km/h. When A passes the position shown, car B is 30 m from the intersection and is accelerating south toward the intersection at the rate of 1.5 m/s2. Determine the acceleration which A appears to have when ...
Sunday, April 14, 2013 at 8:27pm

Physics
A satellite circling the earth completes each orbit in 5.10 x 10^3 s. What is the gravitational field strength @ the location of the satellite's orbit?
Sunday, April 14, 2013 at 8:23pm

physics
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Sunday, April 14, 2013 at 6:50pm

physics
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Sunday, April 14, 2013 at 6:49pm

PHYSICS
A 40 kg child stand on one end of a 70 kg canoe hat is 4 m in length. The boat is initially 3 m from a dock. The child notcies a turtle on a arock near the far en of the canoe so she proceeds to walk to the far ed off the canoe o get the turtle. a) neglecting any friction, ...
Sunday, April 14, 2013 at 6:23pm

Physics
Consider the RL circuit shown in the figure, where R = 5.0 Ω and L = 4.6 H. How much energy is stored in the inductor after the switch has been closed a long time? I would know how to do this if they actually gave me a value for time, but I'm lost now. Can someone ...
Sunday, April 14, 2013 at 6:09pm

Physics
150kg cart is traveling right 3m/s. a 20kg block of coal comes from the cart at 38degrees below the horizontal. The new velocity of the cart with the block is 3.95m/s. What is the initial speed of the coal.
Sunday, April 14, 2013 at 6:04pm

A spring is extended by 4mm when a load of 2.N was applied. a)What is its spring constant? b)How much would it extend if a losd of 150g was suspended from it?
Sunday, April 14, 2013 at 5:38pm

physics
A spring is extended 4mm by an applied force of 2.0N. a)What is its spring constant? b)How much would it extend if a load of 150g was suspended from it?
Sunday, April 14, 2013 at 5:25pm

physics
A spring is extended 4mm by an applied force of 2.0N. a)What is its spring constant? b)How much would it extend if a load of 150g was suspended from it?
Sunday, April 14, 2013 at 5:19pm

physics
A 46.7-g golf ball is driven from the tee with an initial speed of 55.5 m/s and rises to a height of 25.9 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. (b) What is its speed when it is 5.85 m below its highest point?
Sunday, April 14, 2013 at 5:18pm

Physics
A satellite circling the earth completes each orbit in 5.10 x 10^3 s. What is the gravitational field strength @ the location of the satellite's orbit?
Sunday, April 14, 2013 at 5:13pm

Physics
A rotating uniform-density disk of radius 0.6 m is mounted in the vertical plane. The axle is held up by supports that are not shown, and the disk is free to rotate on the nearly frictionless axle. The disk has mass 5.8 kg. A lump of clay with mass 0.5 kg falls and sticks to ...
Sunday, April 14, 2013 at 4:08pm

Physics
11-098-satellite_and_junk.jpg A spherical satellite of radius 4.6 m and mass M = 195 kg is originally moving with velocity vsatellite,i = < 3000, 0, 0 > m/s, and is originally rotating with an angular speed ?1 = 2 radians/second, in the direction shown in the diagram. A ...
Sunday, April 14, 2013 at 4:06pm

Physics
A device consists of eight balls each of mass 0.4 kg attached to the ends of low-mass spokes of length 1.8 m, so the radius of rotation of the balls is 0.9 m. The device is mounted in the vertical plane. The axle is held up by supports that are not shown, and the wheel is ...
Sunday, April 14, 2013 at 4:01pm

pre ap physics
A) A small cork with an excess charge of +9.0x10^-6 is placed 0.13 m from another cork, which carries a charge of −3.2x10^-6. What is the magnitude of the electric force between the corks? The Coulomb constant is 8.98755 × 10^9 N • m^2/C^2. Answer in units of ...
Sunday, April 14, 2013 at 3:33pm

physics
A solid block of mass m2 = 8.3 kg, at rest on a horizontal frictionless surface, is connected to a relaxed spring. The other end of the spring is fixed, and the spring constant is k = 210 N/m. Another solid block of mass m1 = 12.4 kg and speed v1 = 4.9 m/s collides with the 8....
Sunday, April 14, 2013 at 3:23pm

physics
A 22.0 Ω, 11.0 Ω, and 6.00 Ω resistor are connected in parallel to an emf source. A current of 6.00 A is in the 11.0 Ω resistor.What is the potential diﬀerence across the source? Answer in units of V
Sunday, April 14, 2013 at 11:17am

physics
An 8.0 Ω resistor and a 4.0 Ω resistor are connected in series with a battery. The potential diﬀerence across the 4.0 Ω resistor is measured as 9 V. Find the potential diﬀerence across the battery.
Sunday, April 14, 2013 at 10:46am

Physics
Define resistivity and state its units
Sunday, April 14, 2013 at 10:36am

Physics
On an air track, a 403.0 glider moving to the right at 1.70 collides elastically with a 500.5 glider moving in the opposite direction at 3.00 . 1. Find the velocity of first glider after the collision. 2. Find the velocity of second glider after the collision.
Sunday, April 14, 2013 at 10:22am

physics
'a weather station monitors a storm using a radar system. the radio wave pulse emitted is received back at the transmitter after 0.34 ms. the wavelength emitted was 5.6 cm and that received after reflection from the storm was 1 billionth of a meter longer. what information...
Sunday, April 14, 2013 at 8:42am

physics
An elevator has a mass of 500 kg. It may safely carry an additional mass of 1000kg and accelerate upward at 2m/s2. What is the tension in the cable?
Sunday, April 14, 2013 at 7:45am

physics
A thin steel hoop of weight W and radius r starts from rest at A and rolls down along a circular cylindrical surface of radius a as shown in Fig. G. Determine the angle defining the position of point B where the hoop will begin to slip if the coefficient of friction at the ...
Sunday, April 14, 2013 at 1:15am

Physics
A coil consists of N=10^5 turns of wire wrapped uniformly around a plastic torus. The inside radius of the torus is r0=0.15 m and the outer radius is r1=0.16 m. Thus, each winding has a diameter d=0.01 m. What is the self-inductance (in H) of this coil? Work in the ...
Sunday, April 14, 2013 at 1:13am

Physics
Consider the following circuit. We have R_1=7 Ohms, R_2=17 Ohms, R_3=11 Ohms, V=9 Volts, L=0.09 H. At t=0 the switch is closed. (a)Immediately after the switch is closed, what are currents I_1, I_2, I_3 ? I_1 (b)What are the three currents after the switch has been closed for ...
Sunday, April 14, 2013 at 12:56am

physics
A 57.0 kg diver dives from a height of 15.0 m. She reaches a speed of 14.0 m/s just before entering the water. (a) What was the average force of air resistance (e.g., friction) acting on the diver. (b) What is the force of friction underwater if she reaches a depth of 2.5 m ...
Saturday, April 13, 2013 at 11:47pm

physics
A 57.0 kg diver dives from a height of 15.0 m. She reaches a speed of 14.0 m/s just before entering the water. (a) What was the average force of air resistance (e.g., friction) acting on the diver. (b) What is the force of friction underwater if she reaches a depth of 2.5 m ...
Saturday, April 13, 2013 at 11:37pm

physics
A basketball player is balancing a spinning basketball on the tip of his finger. The angular velocity of the ball slows down from 18.0 to 14.7 rad/s, during the slow down the angular displacement is 85.4 rad. Determine the time it takes for the ball to slow down.
Saturday, April 13, 2013 at 10:12pm

physics
A pulley of radius .10 m and having a rotational inertia of .30 kg-m^2 has a cord wrapped around it and attached to a 6.00 kg mass as shown. The pulley is free to rotate about a fixed axis through its center. The mass is allowed to fall from rest. What is the speed of the mass...
Saturday, April 13, 2013 at 4:36pm

physics
A gate is free to rotate without friction about its hinges at H. The gate is initially at rest. A 4.00 kg ball of mud is thrown at 18.0 m/s towards the center of the gate and the path of the mud is perpendicular to the plane of the gate. A) Compute the magnitude of the mud'...
Saturday, April 13, 2013 at 4:33pm

Physics :)
An object has a moment of Inertia of 300 kgm^2. A torque of 94 Nm is applied to the object. What is the angular acceleration of the object? Can someone please explain this to me and help me find the correct answer?! Thank you! :)
Saturday, April 13, 2013 at 3:39pm

Physics
1) a car moving at 50km/h crashes Into the barrier and stops in 0.25 m a) if a 10kg child were to be stopped in the same time , what is the average force must be exerted ? c)approximately what is the mass of an object whose weight equals to the force in Part b?Could you lift ...
Saturday, April 13, 2013 at 2:04pm

Physics
The Circuit contains a resistor R1, Resistor with R2 and an inductance L in series with a battery of emf ε0=V0 . R2 having a switch in parallel, the switch S is initially closed. At t = 0, the switch S is opened, so that an additional very large resistance R2 (with R2>...
Saturday, April 13, 2013 at 12:24pm

Physics
Consider a circuit with an RL series with L=0.09 H and R=0.05 Ohm. At t=0 the circuit is connected to a battery which provides V0=12 V. (a)How long does it take to the current to equal a fraction 0.95 of the steady state current? (b) What is the energy stored (in Joules) in ...
Saturday, April 13, 2013 at 12:08pm

Physics
Consider the process of charging a parallel plate capacitor with circular plates of radius R=5 cm separated by a distance d=0.2 cm. At some time t1, the capacitor is being charged with a current I=0.04 A. Consider a point P on the plane which is equally distant from the two ...
Saturday, April 13, 2013 at 12:05pm

physics
a stone of mass 1 kg is tied to the end of a string 1m long . it is whirled in a vertical circle . if the velocity of the stone at the top be 4m/s , what is the tension in the string ?
Saturday, April 13, 2013 at 3:53am

physics
two similar charged small spheres each having a charge of 0.044 micro coulombs are suspended from a point by a thread of length 15 cm each. at equilibrium the angle is 5 degree. what is the mass of each sphere ?
Saturday, April 13, 2013 at 12:26am

physics
Tarzan (m = 68kg) swings down from a height of 4.8m on a vine to save Jane (m = 35kg) from some hungry hippos. if he gravs jane in an inelastic collision at the bottom of the vine's path, how high will they swing up to after the collision?
Saturday, April 13, 2013 at 12:22am

physics
A 45g golf ball is hit with a golf club. the head of the club has a mass of 0.19kg and travels 63m/s before the collision. the ball has a speed of 72m/s as it leaves the face of the club. what is the speed of the club after the collision?
Saturday, April 13, 2013 at 12:21am

physics
Calculate the number of H2O molecules in a human body of mass 50.6 kg. Assume that, on average, water makes up 62% of the mass of a human body. (Use 1.0 u for the atomic mass of hydrogen, and 16.0 u for the atomic mass of oxygen.)
Friday, April 12, 2013 at 11:00pm

physics
Just wanted to say a quick thanks to Steve and Damon, figured it all out, thanks guys, awsome!!!
Friday, April 12, 2013 at 8:50pm

You are a maker of hot air balloons and wish to construct a balloon that will lift you and a friend to places unknown. Your standard balloon design is a perfectly spherical, nylon fabric balloon with a small hole on the bottom for the burner that heats the air. Nylon starts to...
Friday, April 12, 2013 at 7:41pm

physics
A technician at the top of a 200m tall radio tower drops her hammer. how much time does it take for the hammer to strike the ground?
Friday, April 12, 2013 at 2:44pm

PHYSICS/MATH
What is your average power if you lift a 33.8 kg box at a constant speed to a height of 3.27 m in 6.10 s?
Friday, April 12, 2013 at 2:25pm

PHYSICS/MATH
A mass and spring are arranged on a horizontal, frictionless table. The spring constant is k = 450 N/m, and the mass is 5.4 kg. The block is pushed against the spring so that the spring is compressed an amount 0.35 m, and then it is released. Find the velocity of the mass when...
Friday, April 12, 2013 at 2:24pm

physics
What is the maximum current allowed in a 7.5 W, 300 resistor?
Friday, April 12, 2013 at 1:16pm

Physics
A small steel sphere of mass 0.40 kg is attached by a 0.50 m long cord to a swivel pin set into the surface of a frictionless table top. The sphere moves in a circle on the horizontal surface with a speed of 6.0 m/s. a.) what is the magnitude of the centripetal acceleration of...
Friday, April 12, 2013 at 1:12pm

conceptional physics
If a 35cm radius tire spins at a rate of 72 rad/s what is the rotating speed?
Friday, April 12, 2013 at 12:50pm

Physics multiple choice
3. What are the units for Coeffecient of Lift? [kgm^-3] No units [Ns] [N^2] [N] [ms^-1] [kg] 4. What are the units for the ratio Lift to Drag? [Ns] [kgm^-3] No units [ms^-1] [kg] [N^2] [N]
Friday, April 12, 2013 at 12:48pm

physics
A boat is traveling on a bearing of 25 degrees East of North at a speed of 4 knots (a knot is 1.852 km/h). After traveling for 3 hours, the boats heading is changed to due South and it travels for an additional 2 hours at 5 knots. Using a Vector diagram, what is the resultant...
Friday, April 12, 2013 at 12:43pm

Physics
Consider a regular pyramid charged with constant volume charge density. The potential at point P, the top of the pyramid is 1V. What would be the potential at point P if we removed the top part, so the pyramid is instead truncated at a height h=0.6H? Hint: You don't need ...
Friday, April 12, 2013 at 9:24am

PHYSICS! I CAN NOT GET
A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves moving? ____m/s (I got these answers and ...
Friday, April 12, 2013 at 8:52am

Physics
During a free kick at a soccer playoff game a 0.7 kg ball at the peak of the kick 14.7 m above the field had a kinetic energy of 39.8 J. How fast was the ball booted by the player on the field?
Friday, April 12, 2013 at 8:46am

physics
A bead of mass m = 40.5 kg is released from point A which is located 5 m above the ground and slides on the frictionless track as shown in the figure. Determine the beads speed when it reaches point C which is located 2.0 m above the ground.
Friday, April 12, 2013 at 8:38am

HELP Physics
The average rate at which energy is conducted outward through the ground surface in a certain region is 30.9 mW/m2, and the average thermal conductivity of the near-surface rocks is 3.11 W/m·K. Assuming a surface temperature of 9.48°C, find the temperature (in ...
Friday, April 12, 2013 at 7:40am

physics
A coil consists of N=105 turns of wire wrapped uniformly around a plastic torus. The inside radius of the torus is r0=0.12 m and the outer radius is r1=0.14 m. Thus, each winding has a diameter d=0.02 m. What is the self-inductance (in H) of this coil? Work in the ...
Friday, April 12, 2013 at 12:12am

physics
Consider a circuit with an RL series with L=0.09 H and R=0.05 Ohm. At t=0 the circuit is connected to a battery which provides V0=12 V. (a)How long does it take to the current to equal a fraction 0.95 of the steady state current? (b) What is the energy stored (in Joules) in ...
Friday, April 12, 2013 at 12:11am

physics
Consider the process of charging a parallel plate capacitor with circular plates of radius R=5 cm separated by a distance d=0.2 cm. At some time t1, the capacitor is being charged with a current I=0.075 A. Consider a point P on the plane which is equally distant from the two ...
Friday, April 12, 2013 at 12:10am

physics
Compare the total magnetic energy in two solenoids, each with N turns, area A, and current I, but length x and 2x. Denote Ux the total magnetic energy in the solenoid with length x, and U2x the one in the solenoid with length 2x. What is U2x/Ux?
Friday, April 12, 2013 at 12:09am

physics
Consider the following circuit. 7.3 Ω 3.0 Ω 3.0 Ω 4.5 Ω 1.0 Ω 3.0 Ω 4.5 Ω 19.0 Ω 19.0 Ω 30 V Find the equivalent resistance. Answer in units of Ω
Thursday, April 11, 2013 at 11:26pm

physics
the ﬁgure is 4.00 W. E 3.0 Ω 15.0 Ω 5.0 Ω 4.3 Ω 3.0 Ω Find the equivalent resistance of the circuit. Answer in units of Ω
Thursday, April 11, 2013 at 11:18pm

Physics
An electric force of 3x10^-8N is produced from an electrostatic point charge of 4x10^-10. It is 40cm from another electrostatic point charge. What is the charge of the second point?
Thursday, April 11, 2013 at 11:15pm

Physics
A projectile is fired vertically from Earth's surface with an initial speed v0. Neglecting air drag, how far above the surface of Earth will it go? (Use any variable or symbol stated above along with the following as necessary: ME for the mass of the Earth, rE for the ...
Thursday, April 11, 2013 at 11:15pm

Physics
If an electric force of 550N is produced from two charges, one is 345C, the other is 125C. How far apart are the charges?
Thursday, April 11, 2013 at 11:11pm

physics
During a thunderstorm, the separation between the clouds and the earth acts as a giant capacitor with a capacitance of 2,500 µF (µ is the SI prefix for 10-6). If a tower is struck by a lightning bolt that releases 50 C of charge, how much energy is released?
Thursday, April 11, 2013 at 10:49pm

physics
What wavelength of sound would a bat need to detect a 1cm diameter mosquito? Also, if it took 0.3 seconds for sound to return to a moth how far away would the moth be?
Thursday, April 11, 2013 at 8:57pm

PHYSICS
The string is 0.80 m long with tension 7.00 N. The total mass of the string is 0.012 kg. Find the wavelength of this standing wave in meters
Thursday, April 11, 2013 at 7:54pm

physics
when 100 J of work is done on a stationary flywheel ( that is otherwise free to rotate in place), its angular speed increases from 60 rev/min. What is its moment of inertia?
Thursday, April 11, 2013 at 7:19pm

Physics
Two boys standing on carts that move along a horizontal frictionless surface. The mass of each boy-cart combination is 100 kg, and each moves initially with the velocities of: Boy A 7cm/sec and Boy B: 10cm/sec. The boy on cart A throws a 2kg ball to the boy on Cart B (assume ...
Thursday, April 11, 2013 at 5:56pm

physics
A rocket cruising past earth at 0.800c shoots a bullet out the back door,opposite the rocket's motion,at 0.900c relative to the rocket. What is the bullet's speed relative to the earth?
Thursday, April 11, 2013 at 5:50pm

Physics
4. What does the slope of each of the following graphs stand for? (y versus x) a) mass vs volume b) velocity vs time c) mass vs force d) kinetic energy vs frequency e) sine incident angle vs sine refracted angle f) charge vs voltage g) voltage vs current h) force vs area
Thursday, April 11, 2013 at 5:10pm

physics
A learner with a mass of 40 kg rides on a skate board with a mass of 3 kg. The resultant force on the learner and the skate board is 90 N. Calculate his acceleration.
Thursday, April 11, 2013 at 5:02pm

physics
A learner with a mass of 40 kg rides on a skate board with a mass of 3 kg. The resultant force on the learner and the skate board is 90 N. Calculate his acceleration.
Thursday, April 11, 2013 at 5:02pm

physics
A crate of eggs is located in the middle of the flat bed of a pickup truck as the truck negotiates a curve in the flat road. The curve may be regarded as an arc of a circle of radius 39.6 m. If the coefficient of static friction between crate and truck is 0.630, how fast can ...
Thursday, April 11, 2013 at 4:40pm

physics
In the figure below, a square of edge length s is formed by four spheres of masses, m1, m2, m3, and m4. What is the x-component and the y-component of the net gravitational force from them on a central sphere of mass m5. State your answers in terms of the given variables. (Use...
Thursday, April 11, 2013 at 4:03pm

Physics
In the absence of a nearby metal object, the two inductances (LA and LB) in a heterodyne metal detector are the same, and the resonant frequencies of the two oscillator circuits have the same value of 580.0 kHz. When the search coil (inductor B) is brought near a buried metal ...
Thursday, April 11, 2013 at 2:54pm

Physics!! HELP
A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves moving? _____m/s
Thursday, April 11, 2013 at 2:28pm

Physics
How much work is done pushing a wheel barrow full of cement 5.3m forward if a force of 500N is applied 20 degrees from the vertical?
Thursday, April 11, 2013 at 2:23pm

Physics Electric Force
Particle A of charge 2.76 10-4 C is at the origin, particle B of charge -6.54 10-4 C is at (4.00 m, 0), and particle C of charge 1.02 10-4 C is at (0, 3.00 m). We wish to find the net electric force on C. (a) What is the x component of the electric force exerted by A on C? (b...
Thursday, April 11, 2013 at 2:01pm

Physics
Particle A of charge 2.76 10-4 C is at the origin, particle B of charge -6.54 10-4 C is at (4.00 m, 0), and particle C of charge 1.02 10-4 C is at (0, 3.00 m). We wish to find the net electric force on C.
Thursday, April 11, 2013 at 1:59pm

physics
A boat is traveling on a bearing of 25 degrees East of North at a speed of 4 knots (a knot is 1.852 km/h). After traveling for 3 hours, the boats heading is changed to due South and it travels for an additional 2 hours at 5 knots. Using a Vector diagram, what is the resultant...
Thursday, April 11, 2013 at 12:10pm

physics
Two cylindrical conductors with equal cross sections but different resistivities are put end-to-end. Find the magnitude of the charge that accumulates at the boundary between the conductors if a current I=100A flows in the wires. The wires are made of aluminum and copper with ...
Thursday, April 11, 2013 at 12:07pm

physics
Your written homework will be graded entirely on the clarity and completeness of your derivation. No credit will be awarded for a final answer without a derivation. As usual, simplify your final answers as much as possible. A giant Pez dispenser of mass m rests on a ladder of ...
Thursday, April 11, 2013 at 12:01pm

physics
A 350-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of inertia of 6.00 × 10-6 kg·m2 and a radius of 1.35 cm. The string is pulled vertically downward by a force of 2.50 N. What is the acceleration of the ...
Thursday, April 11, 2013 at 11:11am

physics
Find the work done when a 20 kg sled is pulled across level ground by a rope that makes a 50 deg angle with the horizontal. The sled moves 40 m and the rope is pulled with 10 N of force. If the work done by friction is 240 J, what will happen to the Kinetic Energy of the sled?
Thursday, April 11, 2013 at 10:25am

college physics
Juggles the clown stands on one end of a teeter-totter at rest on the ground. Bangles the clown jumps off a platform 2.5 m above the ground and lands on the other end of the teeter-totter, launching Juggles into the air. Juggles rises to a height of 3.8 m above the ground, at ...
Thursday, April 11, 2013 at 9:56am

physics
A man pushes a packing case of total mass 40kg across a floor at a constant speed of 0.5m/s by exerting a horizontal force of 100N what is the resultant force on the case how big was the force of friction acting on the case how much work was done in 3s what is the Ek into what...
Thursday, April 11, 2013 at 9:27am

Physics
A mirror produces an image that is located 50.0 cm behind the mirror, when the object is located 5.50 cm in front of the mirror. (a) What is the focal length of the mirror? (b) Is the mirror 1 - concave or 2 - convex? (Give the number of the correct answer.)
Thursday, April 11, 2013 at 8:14am

Physics
A small statue has a height of 3.8 cm and is placed in front of a concave mirror. The image of the statue is inverted, 1.9 cm tall, and located 14 cm away from the mirror. Find the focal length of the mirror.
Thursday, April 11, 2013 at 8:13am

Physics
An object that is 32 cm in front of a convex mirror has an image located 17 cm behind the mirror. How far behind the mirror is the image located when the object is 24 cm in front of the mirror?
Thursday, April 11, 2013 at 8:13am

Physics
An object is placed in front of a convex mirror with radius of curvature = 17 cm. The object's height is 3.5 cm and it is initially 25 cm in front of the mirror. Find the (a) location and (b) height of the image. Next the object moves closer to the mirror, so the object ...
Thursday, April 11, 2013 at 8:12am

Physics
An object is placed 11 cm in front of a concave mirror whose focal length is 23 cm. The object is 3.6 cm tall. Determine (a) the location of the image, taking a real image as a positive value and a virtual image as a negative value. (b) Determine the height of the image, where...
Thursday, April 11, 2013 at 8:12am

Physics
A small mirror is attached to a vertical wall, and it hangs a distance of 1.81 m above the floor. The mirror is facing due east, and a ray of sunlight strikes the mirror early in the morning and then again later in the morning. The incident and reflected rays lie in a plane ...
Thursday, April 11, 2013 at 8:11am

heat capacity , physics
if an electric kettle of 5ooW power and water in it,is heated.the temperature change from10-15c for 100 sec.find the heat capacity
Thursday, April 11, 2013 at 8:00am

Physics Hear
1) Peter is heating water on the stove to boil eggs for a picnic. How much heat is required to raise the temperature of his 10.0-kg vat of water from 20.0℃ to 100.0℃? Formula>> Q=mTcp 2)Under the spreading chestnut tree of the village blacksmith dunks red-hot...
Thursday, April 11, 2013 at 6:11am

physics
state the laws of refraction of light
Thursday, April 11, 2013 at 5:29am

Physics
a cars speedometer reads 20 m/s after acceleration from standing start, for 25s. what was the magnitude of acceleration?
Thursday, April 11, 2013 at 4:22am

physics
A little red wagon with mass 8.00 moves in a straight line on a frictionless horizontal surface. It has an initial speed of 3.80 and then is pushed 4.7 in the direction of the initial velocity by a force with a magnitude of 10.0 .
Thursday, April 11, 2013 at 2:25am

physics
Three point charges +q are placed at corners of a square with sides of length L. + + + A B L O What is the potential at point A?
Thursday, April 11, 2013 at 1:54am

physics
One end of a horizontal string is ﬁxed to a wall. A transverse wave pulse in the form of a crest is generated at the other end and moves toward the wall, as shown. Consider the pulse after it has been reﬂected by the wall. v What is/are correct concerning the re...
Thursday, April 11, 2013 at 1:53am

physics
From a cliff that is 8.9 m above a lake, a young woman (mass 44 kg) jumps from rest, straight down into the water. At the instant she strikes the water, what is her de Broglie wavelength?
Thursday, April 11, 2013 at 12:04am

Physics
A microscope is focused on a mark on a table. When the mark is calculated by a glass plate of 3.00cm thick,the microscope has to be raised 1.1cm from the mark to be once more in focus.calculate the refractive index of the glass.
Wednesday, April 10, 2013 at 11:35pm

Physics
A microscope is focused on a mark on a table. When the mark is calculated by a glass plate of 3.00cm thick,the microscope has to be raised 1.1cm from the mark to be once more in focus.calculate the refractive index of the glass.
Wednesday, April 10, 2013 at 11:34pm

physics
a 40 kg student is riding a bicycle to school. the bicycle has a mass of 12 kg. the area that each tire makes contact with the road can be approximated by a rectangle of dimensions 6 cm x 4 cm. what is the pressure that each tire exerts on the road? give your answer in kPa to ...
Wednesday, April 10, 2013 at 11:22pm

physics
a 40 kg student is riding a bicycle to school. the bicycle has a mass of 12 kg. the area that each tire makes contact with the road can be approximated by a rectangle of dimensions 6 cm x 4 cm. what is the pressure that each tire exerts on the road? give your answer in kPa to ...
Wednesday, April 10, 2013 at 11:20pm

physics
a 40 kg student is riding a bicycle to school. the bicycle has a mass of 12 kg. the area that each tire makes contact with the road can be approximated by a rectangle of dimensions 6 cm x 4 cm. what is the pressure that each tire exerts on the road? give your answer in kPa to ...
Wednesday, April 10, 2013 at 11:17pm

Physics
A baseball is thrown horizontally off a cliff with a speed of 7.3 ms-1. What is the vertical distance, to the nearest tenth of a meter, that the ball has fallen after 9.4 seconds?
Wednesday, April 10, 2013 at 9:52pm

physics
The kiloton, which is used to measure the energy released in an atomic explosion, is equal to 4.2 multiplied by 1012 J (approximately the energy released in the explosion of 1000 tons of TNT). Recalling that 1 kilocalorie of energy raises the temperature of 1 kg of water by 1&...
Wednesday, April 10, 2013 at 9:17pm

physics
What is the average speed of a car that travels 210 m in 25 second, then speeds up to 0.47 km in 20 second and then slows down to 150 m in 0.50 minute?
Wednesday, April 10, 2013 at 8:29pm

Physics Heat
1) Peter is heating water on the stove to boil eggs for a picnic. How much heat is required to raise the temperature of his 10.0-kg vat of water from 20.0℃ to 100.0℃? Formula>> Q=mTcp 2)Under the spreading chestnut tree of the village blacksmith dunks red-hot...
Wednesday, April 10, 2013 at 6:30pm

Physics
Suppose you wish to make a solenoid whose self-inductance is 1.8 mH. The inductor is to have a cross-sectional area of 1.60 10-3 m2 and a length of 0.049 m. How many turns of wire are needed? turns
Wednesday, April 10, 2013 at 5:30pm

Physics
A small mirror is attached to a vertical wall, and it hangs a distance of 1.81 m above the floor. The mirror is facing due east, and a ray of sunlight strikes the mirror early in the morning and then again later in the morning. The incident and reflected rays lie in a plane ...
Wednesday, April 10, 2013 at 4:58pm

Physics
A diverging lens has a focal length of -22 cm. Find the image distance when an object is placed 41 cm from the lens.
Wednesday, April 10, 2013 at 4:12pm

Physics
A small statue has a height of 3.8 cm and is placed in front of a concave mirror. The image of the statue is inverted, 1.9 cm tall, and located 14 cm away from the mirror. Find the focal length of the mirror.
Wednesday, April 10, 2013 at 4:11pm

physics
The auroral zone is defined by the last field line from the Earth that returns to the Earth. If the field of the earth extends no further than 10RE in the sunward direction, at what angle (in degrees) in the picture above does the last field line that returns to the earth on ...
Wednesday, April 10, 2013 at 3:36pm

Physics
Red light (n = 1.520) and violet light (n = 1.538) traveling in air are incident on a slab of crown glass. Both colors enter the glass at the same angle of refraction. The red light has an angle of incidence of 20.97°. What is the angle of incidence of the violet light? ...
Wednesday, April 10, 2013 at 3:33pm

Physics
When a converging lens is used in a camera (as in the first drawing), the film must be placed at a distance of 0.240 m from the lens to record an image of an object that is 4.30 m from the lens. The same lens is then used in a projector (as in the second drawing), with the ...
Wednesday, April 10, 2013 at 3:33pm

Physics
A ray of sunlight is passing from diamond into crown glass; the angle of incidence is 36.00°. The indices of refraction for the blue and red components of the ray are: blue (ndiamond = 2.444, ncrown glass = 1.531), and red (ndiamond = 2.410, ncrown glass = 1.520). ...
Wednesday, April 10, 2013 at 3:32pm

Physics
An object that is 32 cm in front of a convex mirror has an image located 17 cm behind the mirror. How far behind the mirror is the image located when the object is 24 cm in front of the mirror?
Wednesday, April 10, 2013 at 3:25pm

Physics
A small mirror is attached to a vertical wall, and it hangs a distance of 1.81 m above the floor. The mirror is facing due east, and a ray of sunlight strikes the mirror early in the morning and then again later in the morning. The incident and reflected rays lie in a plane ...
Wednesday, April 10, 2013 at 3:24pm

Physics
You are trying to photograph a bird sitting on a tree branch, but a tall hedge is blocking your view. However, as the drawing shows, a plane mirror reflects light from the bird into your camera. For what distance must you set the focus of the camera lens in order to snap a ...
Wednesday, April 10, 2013 at 3:23pm

Physics
A magnetic field is perpendicular to the plane of a single-turn circular coil. The magnitude of the field is changing, so that an emf of 0.65 V and a current of 3.4 A are induced in the coil. The wire is the re-formed into a single-turn square coil, which is used in the same ...
Wednesday, April 10, 2013 at 3:00pm

Physics
Which exerts more gravitational force on the baby, Mars or the obstetrician, given that Mars has a mass of 6.4 1023 kg and is 8. 1010 m from Earth?
Wednesday, April 10, 2013 at 2:04pm

physics
Calculate the force of gravity between a newborn baby of mass 4 kg and the obstetrician of mass 80 kg, who is 0.1 m from the baby.
Wednesday, April 10, 2013 at 2:04pm

Physics
Calculate the force of gravity between a human child (mass = 38 kg) and the planet Mars (mass = 6.4 1023 kg), when Mars is at its closest to Earth (distance = 8. 1010 m).
Wednesday, April 10, 2013 at 2:01pm

physics
What is the maximum acceleration a car can undergo if the coefficient of static friction between the tires and the ground is .90
Wednesday, April 10, 2013 at 1:06pm

physics
Venus is a grade 12 learner and she claims that she can shoot a stone 50m vertically high by using a catapult.She wants to know the relationship between the height reached by the stone and the initial velocity of it.
Wednesday, April 10, 2013 at 12:44pm

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