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August 28, 2014

Homework Help: Science: Physics

Recent Homework Questions About Physics

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Physics
A boat takes 2.0hr {\rm hr} to travel 26km {\rm km} down a river, then 6.0hr {\rm hr} to return.
Sunday, February 9, 2014 at 12:04am

Physics
A jet plane has a takeoff speed of Vto=125km/h (34.72 m/s) and it's engines can power it to accelerate with an average acceleration of 5.6 m/s^2. A.) what length of runway will it need to take off safely? B.) suppose it had an available runway length of only 75m. What ...
Saturday, February 8, 2014 at 10:01pm

physics
A car is moving down a highway at -15 m/s and accelerating at 3 m/s^2. If it's initial position is at x = 0 m where will it be after 3 seconds?
Saturday, February 8, 2014 at 9:52pm

Physics
Sound is emitted by a point source. You wish to compare the sound intensity and sound intensity level from this source at two different sites. If the distance to the second site is a factor of 6 greater than the distance to the first, determine the following. (a) Determine the...
Saturday, February 8, 2014 at 8:44pm

Physics
Sound is emitted by a point source. You wish to compare the sound intensity and sound intensity level from this source at two different sites. If the distance to the second site is a factor of 6 greater than the distance to the first, determine the following. (a) Determine the...
Saturday, February 8, 2014 at 7:16pm

Physics
18 cars in a circle at a boom box competition produce a 105 dB sound level at the center of the circle. What is the average sound level produced there by each, assuming interference effects can be neglected? dB = ?
Saturday, February 8, 2014 at 7:15pm

physics
a bead on a wire 30m high is released and reaches point A, where is loops twice towards the right. what is the velocity and acceleration at point A-D? point A is at 20m directly below from starting point. Point B is 10m at the bottom of the first loop. point C is in between ...
Saturday, February 8, 2014 at 7:06pm

Physics
The only force acting on a 4.7 kg body as it moves along the positive x axis has an x component Fx = -6x N, where x is in meters. The velocity of the body at x = 2.4 m is 11 m/s. (a) What is the velocity of the body at x = 4.9 m? (b) At what positive value of x will the body ...
Saturday, February 8, 2014 at 6:51pm

Physics
Two cars pass a school when a stopwatch reads zero. They both travel in the same direction. Car A travels at a constant speed of 98 km/h and Car B travels at 64 km/h. How many meters apart are the two cars when the stopwatch reads 2.0 hours?
Saturday, February 8, 2014 at 4:23pm

Physics
What is the minimum uncertainty in the velocity of an electron that is known to be somewhere between 0.050 nm and 0.10 nm from a proton
Saturday, February 8, 2014 at 4:15pm

Physics
The energy of the first excited state of a hydrogen atom is -0.34 eV ± 0.0003 eV. What is the average lifetime of for this state?
Saturday, February 8, 2014 at 4:11pm

Physics
A trash can with a mass of 5 kg has a coefficient of static friction of μs = 0.80 and a coefficient of kinetic friction of μk = 0.22. (The Active Figure applies to a similar situation, but the values of the mass, coefficient of static friction and coefficient of ...
Saturday, February 8, 2014 at 3:43pm

Physics
Charges of −q and +2q are fixed in place, with a distance of 4.65 m between them. A dashed line is drawn through the negative charge, perpendicular to the line between the charges. On the dashed line, at a distance L from the negative charge, there is at least one spot ...
Saturday, February 8, 2014 at 11:52am

physics
Suppose electrons enter a uniform electric field midway between two plates at an angle ¦È0 to the horizontal, as shown in the figure
Saturday, February 8, 2014 at 11:42am

Physics
You and a friend each drive 54 km. You travel at 95 km/h; your friend travels at 118 km/h. How many minutes will your friend have to wait for you at the end of the trip?
Saturday, February 8, 2014 at 11:35am

physics
Two identical weights of mass M are linked by a thread wrapped around a frictionless pulley with a fixed axis. A small weight of mass ‘m’ is placed on one of the weights. What is reaction force between m and M?
Saturday, February 8, 2014 at 11:05am

physics
2 tall buildings are 200m apart. with what speed a ball be thrown horizontally from a window of one building 2km above the ground so that it will enter a window 40m from the ground in the other?
Saturday, February 8, 2014 at 2:40am

physics
a block of wood of 200g is thrown vetically with a veloncity of 20mls what is the pontential energy?
Saturday, February 8, 2014 at 12:29am

Physics Help, check work?
A running track consists of two straight 88.5m segments and two semicircles of radius 39.0m as shown in the figure. Part A was finding the distance a runner travels in one complete lap. d= 422 m. No problem. Then part B asks for the displacement in x, y components of a runner ...
Friday, February 7, 2014 at 8:47pm

physics
What is the resistance of a 7.4-m length of copper wire 1.2mm in diameter? The resistivity of copper is 1.68×10−8Ω⋅m. R=_________
Friday, February 7, 2014 at 8:30pm

physics
A constant voltage is applied across a circuit. If the resistance in the circuit is doubled, what is the effect on the power dissipated by the circuit? a. The power dissipated is reduced by a factor of 4. b. The power dissipated is quadrupled. c. The power dissipated is ...
Friday, February 7, 2014 at 8:28pm

physics
Consider two copper wires with the same cross-sectional area. Wire A is twice as long as wire B. How do the resistivities and resistances of the two wires compare? CHECK ALL THAT APPLY Wire A and wire B have the same resistance. Wire A has twice the resistivity of wire B. Wire...
Friday, February 7, 2014 at 8:27pm

college physics 2
A current of 2.10A flows in a wire. How many electrons are flowing past any point in the wire per second? N=________________________ electrons/s
Friday, February 7, 2014 at 8:24pm

Physics
You're driving down the highway at 20m/s when you see a snowman you don't want to crush 35 m in front of you. Your reaction time before stepping on the brakes is 0.5s, and acceleration created by your brakes is 10 m/s^2 what was the distance travelled before coming to ...
Friday, February 7, 2014 at 7:21pm

physics
A passenger in a helicopter traveling upwards at 20 m/s accidentally drops a package out the window. If it takes 8 seconds to reach the ground, how high to the nearest meter was the helicopter when the package was dropped?
Friday, February 7, 2014 at 5:09pm

Physics
Landing with a speed of 90 m/s In the x direction a jet come to rest at 1 km. assuming the jet slows down with constant acceleration find the magnitude of it's acceleration. Is there anyway someone could break this down step by step??
Friday, February 7, 2014 at 5:01pm

PHYSICS
A car traveling at 17 m/s accelerates at 1.37 m/s2 for 12 seconds. To the nearest meter how far does it travel?
Friday, February 7, 2014 at 5:00pm

physics
A runner dashes from the starting line (x = 0) to a point 127 m away and then turns around and runs to a point 38 m away from the starting point in 13 seconds. To the nearest tenth of a m/s what is the average speed? What is the runner's average velocity in the previous ...
Friday, February 7, 2014 at 4:58pm

physics
How far to the nearest tenth of a meter can a runner running at 10 m/s run in the time it takes a rock to fall from rest 99 meters? Which is: (127m+89m)/13s= 216m/13s= 16.7m/s But, the second part of the problem is: What is the runner's average velocity? Which I'm not ...
Friday, February 7, 2014 at 4:48pm

physics
How far to the nearest tenth of a meter can a runner running at 10 m/s run in the time it takes a rock to fall from rest 99 meters?
Friday, February 7, 2014 at 4:33pm

physics
Two buses leave downtown one is headed southwest the other is headed northeast. Do they have the same velocity? Why or why not?
Friday, February 7, 2014 at 4:29pm

physics
A person riding in the back of a pickup truck traveling at 60km/h on a straight, level road throws a ball with a speed of 10km/h relative to the truck in the direction of the truck's motion.
Friday, February 7, 2014 at 4:28pm

physics
If the vertical initial speed of the ball is 4.0m/s as the cannon moves horizontally at a speed of 0.70m/s , how far from the launch point does the ball fall back into the cannon?
Friday, February 7, 2014 at 4:24pm

physics
A speeder traveling at 30 m/s passes a motorcycle policeman at rest at the side of the road. The policeman accelerates at 2.4 m/s2. To the nearest tenth of a second how long does it take the policeman to catch the speeder?
Friday, February 7, 2014 at 4:16pm

Physics
An ice chest at a beach party contains 12 cans of soda at 4.16 °C. Each can of soda has a mass of 0.35 kg and a specific heat capacity of 3800 J/(kg C°). Someone adds a 8.48-kg watermelon at 25.7 °C to the chest. The specific heat capacity of watermelon is nearly ...
Friday, February 7, 2014 at 4:13pm

Physics
Ball A is thrown straight down off the top of a tall building with an initial velocity of 20m/s. Ball b is thrown straight up from the top of the same building with initial velocity of 20 m/s. Which ball, if either, experiences the greater acceleration after leaving the ...
Friday, February 7, 2014 at 3:21pm

Physics
An aluminum can is filled to the brim with a liquid. The can and the liquid are heated so their temperatures change by the same amount. The can’s initial volume at 8 °C is 3.5 × 10-4 m3. The coefficient of volume expansion for aluminum is 69 × 10-6 (C°...
Friday, February 7, 2014 at 2:56pm

physics
One gram of nickel has 1.026 × 1022 atoms, and each nickel atom has 28 electrons. How many electrons are contained in 6.00 g of nickel? The elemental charge is 1.6 × 10−19 C. Answer in units of electrons
Friday, February 7, 2014 at 2:52pm

Physics
A dockworker applies a constant horizontal force of 73.0N to a block of ice on a smooth horizontal floor. The frictional force is negligible. The block starts from rest and moves a distance 11.5m in a time 5.40s . a.) What is the mass of the block? b.)If the worker stops ...
Friday, February 7, 2014 at 2:37pm

physics
A wire 1m long and weighting 5 gm is stretched by a tension of 4kg wt. When sounded, it is found to vibrate in two loops. Calculate the frequency of the note emitted by the wire.
Friday, February 7, 2014 at 8:49am

physics
Q. A 200 kg load is suspended by a cable from a crane . Two ropes are attached to the load , acting at 90 deg to each other. One rope exerts a pull of 220 N , at 10 deg below horizontal, the other rope exerts a force of 360 N at 15 deg below horizontal. Calculate 1)tension in ...
Friday, February 7, 2014 at 6:03am

physics
A ball is thrown straight upward from ground level. At what speed must the ball be thrown if it is to reach a maximum height 21 meters above the ground?
Friday, February 7, 2014 at 3:30am

Physics
You pick up a 2.5kg can of paint from the ground and lift it to a height of 1.7m .How much work do you do on the can of paint? You hold the can stationary for half a minute, waiting for a friend on a ladder to take it. How much work do you do during this time?
Friday, February 7, 2014 at 2:59am

physics
he x-component of a velocity vector that has an angle of 44∘ to the +x-axis has a magnitude of 4.3m/s . What is the magnetude velocity?
Friday, February 7, 2014 at 1:32am

physics
wo cars approach each other on a straight, level highway. Car A travels at 60 km/h and car B at 80 km/h. The driver of car B sees car A approaching at a speed of ________. Two cars approach each other on a straight, level highway. Car A travels at 60 and car B at 80 . The ...
Friday, February 7, 2014 at 12:44am

physics
Water of density 1000 kg/m3 falls without splashing at a rate of 0.241 L/s from a height of 81.3 m into a 0.638 kg bucket on a scale. If the bucket is originally empty, what does the scale read 2.06 seconds after the first drop contacts the bucket? The acceleration due to ...
Thursday, February 6, 2014 at 10:59pm

Physics
) The energy of the first excited state of a hydrogen atom is -0.34 eV ± 0.0003 eV. What is the average lifetime of for this state?
Thursday, February 6, 2014 at 10:46pm

Physics
A student is doing the egg blast lab. Their egg blast device has a total mass of 0.20 kg. It fires off of the launcher at 26 m/s. The egg hits the wall, splatters, and stays stuck to the wall. Find the total impulse on the egg.
Thursday, February 6, 2014 at 9:46pm

physics
A proton, initially traveling in the +x-direction with a speed of 6.00×105m/s , enters a uniform electric field directed vertically upward. After traveling in this field for 4.38×10−7s , the proton’s velocity is directed 45 ∘ above the +x-axis.
Thursday, February 6, 2014 at 9:16pm

physics
a 65kg person dives into the water from the 10m platform. she comes to a stop 2m below the surface of the water. what net force did the water exert on the swimmer? so for the net force i got -2548N i know: vf^2=vi^2 + 2ad vf^2 = 0 + 2(9.8)(10) vf^2 = 196 vf=14m/s therefore to ...
Thursday, February 6, 2014 at 7:34pm

physics
What total capacitances can you make by connecting a 4.98 µF and 8.98 µF capacitor together? series ? parallel?
Thursday, February 6, 2014 at 7:27pm

Physics
An atomic nucleus of radon initially moving at 530 m/s emits an alpha particle in the direction of its velocity, and the new nucleus slows to 410 m/s. If the alpha particle has a mass of 4u, and the original nucleus of radon had a mass of 222u, what speed does the alpha ...
Thursday, February 6, 2014 at 6:35pm

Physics
Vertical beam of mercury (Hg atomic mass =202u) atoms emerges from the oven kept at T= 400K. Consider three atoms, emerging from the oven: one with the average speed, one with the rms speed, and the other with the most probable speed of the Maxwellian distribution a) Find the ...
Thursday, February 6, 2014 at 6:06pm

Physics
A 4 liter sample of a diatomic gas with γ =1.4 confined to a cylinder, is carried through a closed cycle. The gas is initially at 1.00atm. and 300K. First, its pressure is tripled under constant volume. Then it expands adiabatically to its original pressure. Finally the ...
Thursday, February 6, 2014 at 6:05pm

Physics
A 0.018 kg bullet traveling 222 m/s penetrates a 3.9 kg block of wood, and exits the block with a velocity of 72 m/s. If the block was stationary on a horizontal frictionless surface before impact, how fast does it move after the bullet exits?
Thursday, February 6, 2014 at 5:55pm

Physics
Suppose a hockey puck slides down a frictionless ramp with an acceleration of 4.70 m/s2. (a)What angle does the ramp make with respect to the horizontal? (b) If the ramp has a length of 6.40 m, how long does it take the puck to reach the bottom? (c) Now suppose the mass of the...
Thursday, February 6, 2014 at 5:51pm

Physics
A car is moving down a street at 67 km/h. A child suddenly runs into the street. If it takes the driver 1.26 s to react and apply the brakes, how many meters will the car have moved before it begins to slow down?
Thursday, February 6, 2014 at 5:27pm

Physics
Suppose a hockey puck slides down a frictionless ramp with an acceleration of 4.70 m/s2. What angle does the ramp make with respect to the horizontal? Please show steps...
Thursday, February 6, 2014 at 4:18pm

physics
A balloonist floating at an altitude of 150m accidently drops his book and starts to ascend at a constant velocity of 1.2m/s. How will the balloon be when the book reaches the ground?
Thursday, February 6, 2014 at 2:48pm

physics
A.Use newtons first law to explain why whiplash occurs? B.why are cars fitted with head rests?
Thursday, February 6, 2014 at 10:18am

Physics
A 2.75kg block of copper at 22C dropped into 5.25kg of water at 12.0C. What is the final temperature of the mixture? Specific heat: water = 4.19J/kgK copper = 390J/kgK
Thursday, February 6, 2014 at 6:39am

Physics
Can you please help with the following: x^2+2x-35=0 I can't remember how to get the different possibilities. Appreciate help, thanks
Thursday, February 6, 2014 at 6:21am

Physics
A small rock is thrown vertically upward with a speed of 17.0m/s from the edge of the roof of a 32.0m tall building. The rock doesn't hit the building on its way back down and lands in the street below. Air resistance can be neglected. What is the speed of the rock just ...
Thursday, February 6, 2014 at 1:38am

Physics
What is the weight of a 22.0 kg mass at the equator on the surface of Saturn? The mass of Saturn is 5.69 x 10^26 kg and the radius of Saturn is 6.03 x 10^7 m I tried this one using the equation : Fg= Gm1m2/r^2 Fg= (6.67 x 10^-11)(22.0kg)(5.69 x 10^26kg) / (6.03 x 10^7m)^2 I ...
Wednesday, February 5, 2014 at 11:54pm

Physics
You can use any coordinate system you like in order to solve a projectile motion problem. To demonstrate the truth of this statement, consider a ball thrown off the top of a building with a velocity v at an angle θ with respect to the horizontal. Let the building be 49.0 ...
Wednesday, February 5, 2014 at 11:17pm

Physics
You can use any coordinate system you like in order to solve a projectile motion problem. To demonstrate the truth of this statement, consider a ball thrown off the top of a building with a velocity v at an angle θ with respect to the horizontal. Let the building be 49.0 ...
Wednesday, February 5, 2014 at 11:09pm

physics
in a modern nonlinear dynamic experiment, small beads are vibrated on a plate; when the beads start to move, interesting patterns form. If the plate vibrates at 250 hz, for what amplitude of motion will the bears start to lift off?
Wednesday, February 5, 2014 at 11:04pm

Physics
A speedboat increases in speed from 21 m/s to 30.9 m/s in a distance 191 m. a)Find the magnitude of its acceleration. Answer in units of m/s^2. b)Find the time it takes the boat to travel this distance. Answer in units of s.
Wednesday, February 5, 2014 at 10:20pm

physics
5. A charge of -5.00 nC and a charge of -2.00 nC are separated by a distance of 40.0 cm. Find the equilibrium position (where the net force equals zero) for a third charge of 15.0 nC.
Wednesday, February 5, 2014 at 7:56pm

physics
A 2.0 kg mass rests on a frictionless wedge that has an acceleration of 15 m/s2 to the right. The mass remains stationary relative to the wedge, moving neither higher nor lower. (a) What is the angle of inclination, θ, of the wedge, i.e., the angle between the inclined ...
Wednesday, February 5, 2014 at 7:04pm

physics
You have designed a rocket to be used to sample the local atmosphere for pollution. It is fired vertically with a constant upward acceleration of 15 m/s2. After 21 s, the engine shuts off and the rocket continues rising (in freefall) for a while. (Neglect any effects due to ...
Wednesday, February 5, 2014 at 6:54pm

Physics
A football is kicked at ground level with a speed of 17.9m/s at an angle of 39.0∘ to the horizontal. How much later does it hit the ground?
Wednesday, February 5, 2014 at 6:49pm

Physics
A 500.0 kg object is attached by a rope through a pulley to a paddle-wheel shaft that is placed in a well-insulated tank holding 25.0 kg of water. The object is allowed to fall, causing the paddle wheel to rotate, churning the water. If the object falls a vertical distance of ...
Wednesday, February 5, 2014 at 6:26pm

physics (clear answer)
An airplane traveling north at 400 m/s is accelerated due east at a rate of 50 m/s2 for 6 s. If the effects of air resistance and gravity are ignored, what is the final speed of the plane?
Wednesday, February 5, 2014 at 6:23pm

physics
A 101.6-N bird feeder is supported by three cables as shown in the figure below. Find the tension in each cable
Wednesday, February 5, 2014 at 6:22pm

physics
you are driving up a long, inclined road . after 1.20 mi you notice that signs along the roadside indicate that your elevation has increased by 550 ft.
Wednesday, February 5, 2014 at 6:20pm

Physics
What is the temperature increase of water per kilogram at the bottom of a 145 m waterfall if all of the initial potential energy is transferred as heat to the water?
Wednesday, February 5, 2014 at 6:18pm

Physics
A 3.00 gram lead bullet travels at a speed of 240 m/s and hits a wooden post. If half the heat energy generated remain with the bullet, what is the increase in temperature of the embedded bullet? (clead = 128 J/kg C)
Wednesday, February 5, 2014 at 6:16pm

physics
Two boxes are connected by a cord running over a pulley as shown in the picture below. Box I of mass 8.0 kg is on the top of the table; the coefficient of kinetic friction between box I and the table is 0.10. Box II has a mass of 15.0 kg. What is the tension in the cord? 35 N ...
Wednesday, February 5, 2014 at 6:10pm

physics
As a rock of mass 3.0 kg drops from the edge of a 60. meter high cliff, it experiences air resistance, whose average strength during the fall is 22. N. At what speed will the rock hit the ground? Answer 1.5 m/s 13 m/s 18 m/s 26 m/s 34 m/s
Wednesday, February 5, 2014 at 6:10pm

physics
A 15.0-kg box is released from rest on a rough inclined plane tilted at an angle of 45° to the horizontal. The coefficient of kinetic friction between the box and the inclined plane is 0.200. What is the force of kinetic friction on the box? Answer Fifteen square root of ...
Wednesday, February 5, 2014 at 6:07pm

physics
A basketball is launched with an initial speed of 10.0 m/s and follows the trajectory shown. The height of the basket y= 1.50m.From what distance x the ball is shot? Note: The drawing is not to scale. Angle is 45degrees
Wednesday, February 5, 2014 at 5:40pm

physics
A puck is moving on an air hockey table. Relative to an x, y coordinate system at time t = 0 s, the x components of the puck's initial velocity and acceleration are v0x = +5.2 m/s and ax = +5.9 m/s2. The y components of the puck's initial velocity and acceleration are ...
Wednesday, February 5, 2014 at 5:36pm

Physics
You are pulling a crate across the floor. The crate has a mass of 75.0 kg. You exert a horizontal force of 120. N to the left. Friction exerts a force of 82.0 N to the right. What is the magnitude (fill in box) and direction of the acceleration of the crate?
Wednesday, February 5, 2014 at 5:26pm

physics
A student pulls a box of books on a smooth horizontal floor with a force of 100 N in a direction of 30° above the horizontal. If the mass of the box and the books is 40.0 kg, what is the acceleration of the box? Square root of three meters per second squared. Four square ...
Wednesday, February 5, 2014 at 5:25pm

Physics
) What is the minimum uncertainty in the velocity of an electron that is known to be somewhere between 0.050 nm and 0.10 nm from a proton?
Wednesday, February 5, 2014 at 5:06pm

physics
The wavelength of a pulse is 0.1925mm. There are 5 cycles in the pulse. What is the spatial pulse length?
Wednesday, February 5, 2014 at 4:55pm

physics
The pulse duration of the transducer is 0.6 microseconds. The frequency of the transducer is 8MHz. How many cycles are contained in that pulse?
Wednesday, February 5, 2014 at 4:54pm

physics
what is the propagation speed of a 5MHz transducer?
Wednesday, February 5, 2014 at 4:53pm

physics
What is the wavelength of a 4MHz transducer?
Wednesday, February 5, 2014 at 4:51pm

physics
If an ultrasound beam at the focal zone has a power of 0.050 watts and the area at this focal zone is 4cm^2, what is the intensity of the beam?
Wednesday, February 5, 2014 at 4:50pm

Physics
If you can throw a stone straight up to a height of 18m, how far could you throw it horizontally over level ground? Assume the same throwing speed and optimum launch angle.
Wednesday, February 5, 2014 at 4:50pm

Physics
If the period of a transducer is 0.83msec, what is the HZ?
Wednesday, February 5, 2014 at 4:48pm

physics
If the frequency of a transducer is 5MHz, what is the period?
Wednesday, February 5, 2014 at 4:47pm

physics
Find the length of a simple pendulum that has a period of 5.00s . Assume g = 9.81 m/s2. Express your answer to three significant figures and include the appropriate units.
Wednesday, February 5, 2014 at 4:41pm

Physics
If the period of the moon were 31 days while its orbit radius 3.8x10^8m, what would the mass of the Earth be?
Wednesday, February 5, 2014 at 3:21pm

Physics
Two trains, each having a speed of s, are headed at each other on the same straight track. A bird that can fly at speed 2s flies off the front of one train when they are d apart and heads directly for the other train. On reaching the other train it flies directly back to the ...
Wednesday, February 5, 2014 at 2:10pm

Physics
A particle starts from the origin at t = 0 and moves along the positive x axis. A graph of the velocity of the particle as a function of the time is shown in the figure; the v-axis scale is set by vs = 7.0 m/s. (a) What is the coordinate of the particle at t = 5.0 s? (b) What ...
Wednesday, February 5, 2014 at 2:09pm

physics
A red ball of mass 0,6 kg,travelling at 5 m.s^-1 on a frictionless surface ,stikes a stationary green ball of mass 0,3 kg.after the collision,the red ball continues to move in its original direction at 2m.s^-1,while the green ball moves in front of the red ball. Determine the ...
Wednesday, February 5, 2014 at 1:52pm

physics
thanks for the answer but can i get more explanation
Wednesday, February 5, 2014 at 12:40pm

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