Saturday

July 26, 2014

July 26, 2014

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**physics**

A force of 15 N (delivered by a cue) acts on a billiard ball for 0.01 s. Find the magnitude of the a. acceleration of the ball b. final speed of the ball c. distance over which the cue was in contact with the ball
*Friday, March 14, 2014 at 8:46pm*

**Physics**

Two cars are parked on a street. A third car hits the back of the second car and causes all of the cars to move. (Ignore the distance between the cars). Calculate: (a)The acceleration of the whole system; (b)the net force on each car; (c)the contact force that each car exerts ...
*Friday, March 14, 2014 at 7:57pm*

**Physics**

A mountain climber dangles his water bottle and feels the bottle makes an angle of 25 degrees with respect to the vertical line. If his acceleration takes 18 seconds, calculate the speed of the climber.
*Friday, March 14, 2014 at 7:06pm*

**Physics**

Two lovebirds are held together by a stange force called love. Physicists recently discovered the functional form of love (a conservative force) as a function of distance, for lovebirds. Flove(x)=2x^2+3x^3. (units in meters) Assuming they start off next to each other, how much...
*Friday, March 14, 2014 at 4:24pm*

**Physics**

A particle leaves the origin with an initial velocity v=(3.68i) m/s and a constant acceleration a=(-3.33i-3.72j)m/s^2. When the particle reaches its maximum x coordinate, what are (a) its velocity, (b) its position vector?
*Friday, March 14, 2014 at 3:45pm*

**Physics**

The acceleration of a particle moving only on a horizontal xy plane is given by a=5ti+6tj, where a is in meters per second-squared and t is in seconds. At t=0, the position vector r=(19.0m)i+(39.0m)j locates the particle, which then has the velocity vector v=(5.70m/s)i+(3.40m/...
*Friday, March 14, 2014 at 3:43pm*

**Physics**

Assume a spring has an un-stretched length Xo. Write an expression for the elastic potential energy of the spring in terms of the position of the end of the spring X and its spring constant K.
*Friday, March 14, 2014 at 3:06pm*

**urgent (physics)**

A 2 kg brick falls at 5.1 m/s from a height of 6 m above a spring that has a spring constant of 47 N/m. The brick strikes and compresses the spring until it stops moving. Ignore friction effects. How much is the spring compressed by the brick? Assume that there is no Eg after ...
*Friday, March 14, 2014 at 2:43pm*

**Physics**

A skater with an initial speed of 5.90 m/s stops propelling himself and begins to coast across the ice, eventually coming to rest. Air resistance is negligible. (a) The coefficient of kinetic friction between the ice and the skate blades is 0.125. Find the deceleration caused ...
*Friday, March 14, 2014 at 1:24pm*

**Physics**

A car starts from rest and moves with uniform acceleration of 0.3 meter per second. After 30 second, find the velocity of the car and distance covered?
*Friday, March 14, 2014 at 1:06pm*

**Physics**

A 2 kg brick falls at 5.1 m/s from a height of 6 m above a spring that has a spring constant of 47 N/m. The brick strikes and compresses the spring until it stops moving. Ignore friction effects. How much is the spring compressed by the brick? Assume that there is no Eg after ...
*Friday, March 14, 2014 at 12:31pm*

**Physics**

A 2 kg brick falls at 5.1 m/s from a height of 6 m above a spring that has a spring constant of 47 N/m. The brick strikes and compresses the spring until it stops moving. Ignore friction effects. How much is the spring compressed by the brick? Assume that there is no Eg after ...
*Friday, March 14, 2014 at 12:28pm*

**physics**

A chemist is working with a 4.50 mol sample of an ideal gas. The internal energy of the sample is known to be 14,900 J. What is the average kinetic energy of each gas molecule?
*Friday, March 14, 2014 at 12:21pm*

**I need help (Physics)**

A 28 kg ball initially at rest rolls down a 159 m hill. When the ball reaches the bottom it is traveling at 31.3 m/s. How much energy is dissipated by friction on the ball?
*Friday, March 14, 2014 at 12:02pm*

**physics**

A 15.7 kg block is at rest on a ramp, whose angle is 12.1 degrees from the horizontal. How much Normal Force is acting on the block?
*Friday, March 14, 2014 at 11:25am*

**Physics**

A 28 kg ball initially at rest rolls down a 159 m hill. When the ball reaches the bottom it is traveling at 31.3 m/s. How much energy is dissipated by friction on the ball?
*Friday, March 14, 2014 at 11:23am*

**physics-impulse**

A tennis ball of mass m = 0.068kg and speed v = 21m/s strikes a wall at a 45∘ angle and rebounds with the same speed at 45 What is the magnitude of the impulse given to the ball?
*Friday, March 14, 2014 at 11:22am*

**Physics**

Stan the strongman lifts a 524 kg dumbbell from the floor to 1.69 meters above the floor at a constant velocity. How much energy does it take Stan to lift the dumbbell?
*Friday, March 14, 2014 at 11:21am*

**Physics**

A stream of water flows through a small hole at depth h = 10 cm in a tank holding water to height H =40 cm. At what distance x (in cm) does the stream strike the floor? (Neglect air resistance).
*Friday, March 14, 2014 at 10:51am*

**Physics**

A rope is wound round a fixed cylinder of radius r so as to make n complete turns . Show that if one end of the rope is held by a force f, a force f e^2(pi)nu must be applied to the other end to produce slipping,where u is the coeff. of friction between rope and cylinder.
*Friday, March 14, 2014 at 10:50am*

**Physics**

A traffic light is hanging from two cables tilted at 37 and 42 degrees. If it has a mass of 2.3 kg find the tension in each cable.
*Friday, March 14, 2014 at 9:37am*

**Physics**

A freight train has a mass of 4.78 * 10^7 kg. the locomotive provides a force of 1.3 * 10^6 N and the brakes provide a force of -3.2 * 10^3 N. 1. How long will it take for the train to accelerate to it's maximum speed of 15 m/s? 2. The train accidentally stumbles into an ...
*Friday, March 14, 2014 at 9:36am*

**physics**

A child in a boat throws a 5.15-kg package out horizontally with a speed of 10.0 m/s. The mass of the child is 24.2kg and the mass of the boat is 33.2kg . Calculate the velocity of the boat immediately after, assuming it was initially at rest.
*Friday, March 14, 2014 at 9:02am*

**physics**

What is the gravitational field strength at a height h above the surface of the Earth? R is the radius of the earth gR2(R+h)2 gR(R+h) g(R−h)R g(R−h)2R2 2 The instrument used for experimental determination of the value of the universal gravitational constant G is ...
*Friday, March 14, 2014 at 7:24am*

**physics**

An object is thrown upward from the edge of a tall building with a velocity of 10 m/s. Where will the object be 3 s after it is thrown? Take g=10ms−2
*Friday, March 14, 2014 at 7:16am*

**physics**

Croquet ball A moving at 8.0m/s makes a head on collision with ball B of equal mass and initially at rest. Immediately after the collision ball B moves forward at 7.1m/s . What fraction of the initial kinetic energy is lost in the collision?
*Friday, March 14, 2014 at 2:02am*

**Physics**

A 295kg box is pulled at a constant speed by the little engine. The box moves a distance of 2.8 m across the horizontal surface. (μ=.20) How much energy is transferred by the engine? (How much WORK is done?)
*Friday, March 14, 2014 at 12:17am*

**physics**

A coin is dropped from a height of 40 meters. How fast is the coin traveling after 3 seconds?
*Thursday, March 13, 2014 at 6:33pm*

**Physics**

Assume a spring has an un-stretched length Xo. Write an expression for the elastic potential energy of the spring in terms of the position of the end of the spring x and its spring constant k.
*Thursday, March 13, 2014 at 6:20pm*

**Physics**

Consider the gravitational potential, kinetic, and total mechanical energies of a cart moving down an inclined ramp. (Also, let gravitational potential energy be defined to be zero when the cart is at the bottom of the ramp. A. Write an expression for the gravitational ...
*Thursday, March 13, 2014 at 6:19pm*

**physics**

A plane is found by radar to be flying 5.9 km above the ground. The angle of elevation from the radar to the plane is 78.6°. Ten seconds later, the plane is directly over the station. Find the speed of the plane, assuming that it is flying level.
*Thursday, March 13, 2014 at 5:04pm*

**Physics**

A rope is wound round a fixed cylinder of radius r so as to make n complete turns . Show that if one end of the rope is held by a force f, a force f e^2(pi)nu must be applied to the other end to produce slipping,where u is the coeff. of friction between rope and cylinder. Find...
*Thursday, March 13, 2014 at 4:07pm*

**physics**

A rope is wound round a fixed cylinder of radius r so as to make n complete turns . Show that if one end of the rope is held by a force f, a force f e^2(pi)nu must be applied to the other end to produce slipping,where u is the coeff. of friction between rope and cylinder. Find...
*Thursday, March 13, 2014 at 3:58pm*

**Physics**

A swimming pool has dimensions 26 m x 32 m and a flat bottom. When the pool is filled to a depth of 3 m with fresh water, what is the total force due to the water on the bottom?
*Thursday, March 13, 2014 at 2:42pm*

**Physics**

If you wish to warm 100 kg of water by 20° C for your bath, show that 8370 kJ of heat is required.?
*Thursday, March 13, 2014 at 1:43pm*

**Physics**

A 97 kg person slides down a pole, just for fun. The pole has a frictional force of 810 N and the speed of the person at the bottom of the pole is 3.7 meters per second. How long was the pole?(? m)
*Thursday, March 13, 2014 at 11:34am*

**physics**

The charge carried by one electron is e = -1.6 × 10-19 C. The number of electrons necessary to produce a charge of -1.0 C is:
*Thursday, March 13, 2014 at 9:21am*

**physics**

A brass ball weighs 270gram in air and when it was immersed in water,it displaced 30 ml of water .how much will the ball weigh in water?
*Thursday, March 13, 2014 at 8:33am*

**Physics**

Ken has five 200W security lights on outside of home. How much energy do the security lights use in 8 hrs? If the cost of electricity is 8 cents per kWh,what is the cost of operating the security lights ? Please help I'm not sure which formula to use?
*Wednesday, March 12, 2014 at 11:45pm*

**physics**

A boy with a mass of 50 kg is hanging from a spring with a spring constant of 200 N/m. With what frequency does the boy bounce up and down?
*Wednesday, March 12, 2014 at 11:39pm*

**physics**

a car thats 1000 kg is stopped and the brakes exert a force of 3000 N over a distance of 891 meter, how much work is done?
*Wednesday, March 12, 2014 at 6:09pm*

**Physics**

A car of mass m moving at a speed v1 collides and couples with the back of a truck of mass 3m moving initially in the same direction as the car at a lower speed v2. (Use any variable or symbol stated above as necessary.) (b) What is the change in kinetic energy of the car&#...
*Wednesday, March 12, 2014 at 6:02pm*

**Physics**

A carnival seat and a passenger has a combined weight of 193. As the seat is spun on a 18m rope tethered to a pole at an angle of 59.2 degrees, at what speed is the seat traveling?
*Wednesday, March 12, 2014 at 5:27pm*

**Physics**

A 71 kg girl dives off a raft 2.34 square meters floating in a freshwater lake. By how much does the raft rise in cm? Write your answer correct to two decimal places.
*Wednesday, March 12, 2014 at 5:16pm*

**physics**

A glider with a mass of 3 kg is moving rightward at a speed of 2 m/s on a frictionless horizontal air track. It collides with a stationary glider whose mass is 18 kg. If the collision is elastic, what is the speed of the gliders after the collision? Use SI units in your answer...
*Wednesday, March 12, 2014 at 4:36pm*

**Physics**

How large an average force is required to stop a 1400-kg car in 5.0 s if the car’s initial speed is 25 m/s?
*Wednesday, March 12, 2014 at 12:13pm*

**Physics**

Consider a simple frictionless roller-coaster. It begins at x = 0, at a height of y = H. Then it drops into a dip, reaching a minimum at x = 100, with zero height (y = 0). Finally, it goes back up at x = 200, but only reaches a height of y = H/2. Assume the roller-coaster car ...
*Wednesday, March 12, 2014 at 12:07pm*

**Physics**

a) A bullet (m = 0.0250 kg) is fired with a speed of 91.00 m/s and hits a block (M = 2.80 kg) supported by two light strings as shown, stopping quickly. Find the height to which the block rises. b)Find the angle (in degrees) through which the block rises, if the strings are 0....
*Wednesday, March 12, 2014 at 12:05pm*

**Physics**

Two children are playing a game in which they try to hit a small box on the floor with a marble fired from a spring-loaded gun that is mounted on a table. The target box is 3.46 m horizontally from the edge of the table. Bobby compresses the spring 0.97 cm, but the center of ...
*Wednesday, March 12, 2014 at 12:04pm*

**Physics**

Use the following information to calculate the speed of a ball in a pinball machine at a specific location. The ball is launched by using a spring (k = 703 N/m) compressed by 9.0 cm. Consider the starting position of the ball to be its location when the spring is compressed. ...
*Wednesday, March 12, 2014 at 12:03pm*

**Physics**

True or false Consider a simple frictionless roller-coaster. It begins at x = 0, at a height of y = H. Then it drops into a dip, reaching a minimum at x = 100, with zero height (y = 0). Finally, it goes back up at x = 200, but only reaches a height of y = H/2. Assume the ...
*Wednesday, March 12, 2014 at 12:03pm*

**Physics**

Alfonso and Sarah like to go sky diving together. Alfonso has a mass of 86.0 kg and Sarah has a mass of 57.8 kg. While in free fall together (next to each other), Alfonso pushes Sarah horizontally with a force of 12.9 N. What is the magnitude of Alfonso's horizontal ...
*Wednesday, March 12, 2014 at 11:56am*

**Physics**

Stan the strongman lifts a 524 kg dumbbell from the floor to 1.69 meters above the floor at a constant velocity. How much energy does it take Stan to lift the dumbbell?
*Wednesday, March 12, 2014 at 11:49am*

**Physics**

If I stop my 1000 kg car by applying a force with my brakes equal to 3000 N in a distance of 719 meters, how much work is done. (Pay attention to the direction of the force and the displacement)(? J)
*Wednesday, March 12, 2014 at 11:30am*

**Physics**

How fast can a car be going around a turn with radius 42.3 m if the road is covered with ice? (The μs for rubber on ice is 0.10)? Give your answer in miles per hour.
*Wednesday, March 12, 2014 at 11:29am*

**Physics**

A 3.3 kg pendulum bob hangs from a 2 meter string. It is pulled to the side, position A, so that the bob is 103 cm (h on the sketch) above the lowest position, position C. The bob is released and begins to swing. a) What is its potential energy after it has swung to position B...
*Wednesday, March 12, 2014 at 9:24am*

**Physics**

A bead of mass m = 33.5 kg is released from point A which is located 5 m above the ground and slides on a frictionless track. Determine the bead's speed when it reaches point C which is located 2.0 m above the ground.
*Wednesday, March 12, 2014 at 9:20am*

**Physics**

1. A standard LP record has a diameter of 30 centimeters. A record on a standard turntable rotates 33.3 times a minute. What is the centripetal acceleration of a point on the edge of the record? 2.If a 7.3 gram coin is placed at the very edge of the record described in the ...
*Wednesday, March 12, 2014 at 9:09am*

**physics**

A spring cannon is fastened to a glider at rest on a horizontal frictionless air track. The combined mass of the cannon and the glider is 0.560kg. The cannon fires a ball with a mass of 50g horizontally at a speed of 14 m/s. How fast does the cannon-glider assembly move ...
*Wednesday, March 12, 2014 at 12:55am*

**URGENT physics**

The escape velocity of a bullet from the surface of planet Y is 1695 m/s. Calculate the escape velocity from the surface of the planet X if the mass of planet X is 1.37 times that of Y, and its radius is 0.887 times the radius of Y (in m/s).
*Tuesday, March 11, 2014 at 11:37pm*

**URGENT physics**

M1 is a spherical mass (38.6 kg) at the origin. M2 is also a spherical mass (10.3 kg) and is located on the x-axis at x = 59.8 m. At what value of x would a third mass with a 20.0 kg mass experience no net gravitational force due to M1 and M2?
*Tuesday, March 11, 2014 at 11:36pm*

**Physics**

The figure(Figure 1) shows a solid metal sphere at the center of a hollow metal sphere. Assume that E=1.2×104N/C. What is the total charge on the exterior of the inner sphere?
*Tuesday, March 11, 2014 at 10:20pm*

**Physics 141**

A mine car (mass mcar = 444 kg) rolls at a speed of vcar = 0.52 m/s on a horizontal track, as the drawing shows. An mcoal = 141 kg chunk of coal has a speed of vcoal = 0.79 m/s when it leaves the chute. Determine the speed of the car-coal system after the coal has come to rest...
*Tuesday, March 11, 2014 at 10:14pm*

**Physics 141**

A wagon is rolling forward on level ground. Friction is negligible. The person sitting in the wagon is holding a rock. The total mass of the wagon, rider, and rock is 93.0 kg. The mass of the rock is 0.320 kg. Initially the wagon is rolling forward at a speed of 0.520 m/s. ...
*Tuesday, March 11, 2014 at 9:51pm*

**Physics 141**

A 45.0-kg skater is traveling due east at a speed of 2.85 m/s. A 72.5-kg skater is moving due south at a speed of 7.35 m/s. They collide and hold on to each other after the collision, managing to move off at an angle θ south of east, with a speed of vf. Find the following...
*Tuesday, March 11, 2014 at 9:00pm*

**math**

2. How is the graph of y = –2x² – 5 different from the graph of y = –2x²? (1 point) It is shifted 5 units up. It is shifted 5 units down. It is shifted 5 units left. It is shifted 5 units right. 3. A model rocket is launched from a roof into a large ...
*Tuesday, March 11, 2014 at 8:22pm*

**physics**

The escape velocity of a bullet from the surface of planet Y is 1695 m/s. Calculate the escape velocity from the surface of the planet X if the mass of planet X is 1.37 times that of Y, and its radius is 0.887 times the radius of Y (in m/s).
*Tuesday, March 11, 2014 at 7:56pm*

**physics**

Find the speed of a satellite in a circular orbit around the earth with a radius 2.69 times the mean radius of the earth; Radius Earth= 6.37E+3km; Mass Earth= 5.98E+24kg.
*Tuesday, March 11, 2014 at 7:51pm*

**physics**

A 50-kg box is being pushed a distance of 7.1 m across the floor by a force whose magnitude is 175 N. The force is parallel to the displacement of the box. The coefficient of kinetic friction is 0.19. Determine the work done on the box by each of the four forces that act on ...
*Tuesday, March 11, 2014 at 7:23pm*

**physics**

M1 is a spherical mass (38.6 kg) at the origin. M2 is also a spherical mass (10.3 kg) and is located on the x-axis at x = 59.8 m. At what value of x would a third mass with a 20.0 kg mass experience no net gravitational force due to M1 and M2?
*Tuesday, March 11, 2014 at 7:22pm*

**physics **

Starting from rest, a 2.1x10-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts an average upward force of 0.37 N on it. This force does 1.5x10-4 J of work on the flea. (a) What is the flea's speed when it leaves the ground...
*Tuesday, March 11, 2014 at 7:00pm*

**PHYSICS**

The model airplane in Figure 5.6 is flying at a speed of 13.6 m/s on a horizontal circle of radius 19.1 m. The mass of the plane is 1.20 kg. The person holding the guideline pulls it in until the radius of the circle becomes 10.6 m. The plane speeds up, and the tension in the ...
*Tuesday, March 11, 2014 at 6:19pm*

**physics**

Carmen is standing on a giant skateboard that is initially at rest. If we ignore frictional effects with the floor, what is the momentum of the skateboard if Carmon walks to the right with a momentum of 500 ? A. 500 to the right B. 500 to the left C. zero D. 500 thought it ...
*Tuesday, March 11, 2014 at 2:34pm*

**physics**

Under what conditions is mass conserved? A. Whenever the system is isolated or closed. B. Only when the change is a chemical one. C. Always. D. Only when the change is a physical one. I was thinking A.
*Tuesday, March 11, 2014 at 2:32pm*

**physics**

If Earth's mass were suddenly and magically reduced to half its present value, the Sun's gravitational force on Earth would A. be reduced by a factor of 2. B. be reduced by a factor of 4. C. increase by a factor of 2. D. remain the same. I was told it remained the same...
*Tuesday, March 11, 2014 at 2:20pm*

**physics**

22. On the surface of a certain planet, there is one unit of gravitational force exerted on every 0.4 units of mass. The gravitational field strength on this planet has numerical value A. 0.4 B. 2.5 C. 1.6 D. 1 C.1.6 is wrong
*Tuesday, March 11, 2014 at 2:18pm*

**physics**

If you double the radius of a sphere, its volume increases by what factor? A. 8 B. 6 C. 2 D. 4 I thought maybe C.2 or D.4
*Tuesday, March 11, 2014 at 2:16pm*

**physics**

Your instructor rides on a merry-go-round turning at a constant rate. In which direction does the net force on your instructor point? A. away from the center B. toward the center C. down D. tangent to the circular path I choose D.tangent to the circular path (wrong again)
*Tuesday, March 11, 2014 at 2:14pm*

**physics**

A bug rides on a phonograph record. In which direction does the change in velocity of the bug point? A. toward the center of the record B. tangent to the circular path C. away from the center of the record D. up I thought C.away from the center of the record.
*Tuesday, March 11, 2014 at 2:12pm*

**physics**

If a ball is dropped from rest, it will fall 5 m during the first second. How far will it fall during the second second? A. 15 meters B. 10 meters C. 5 meters D. 20 meters the way the question is worded it seems it should be 10meteres but I think it wants total so would it be ...
*Tuesday, March 11, 2014 at 2:09pm*

**physics**

Which of the following could be considered to be an 'accelerator' in an automobile? A. brake pedal B. gas pedal (choose this one but says wrong) C. steering wheel D. All of these can cause the car to accelerate.
*Tuesday, March 11, 2014 at 2:06pm*

**Physics**

A group of swimmers is resting in the sun on an off shore raft. They estimate that 2.9 meters separates a trough and an adjacent crest of surface waves on the lake. In addition, they count 12 crests that pass by the raft in 16 seconds. What is the Period of these waves?
*Tuesday, March 11, 2014 at 12:36pm*

**Physics**

A hiker shouts towards a vertical cliff 305 meters away. The echo is heard 1.85 seconds later. How fast did the sound wave travel in air?
*Tuesday, March 11, 2014 at 12:27pm*

**physics**

A father (m= 90 kg) and son (m= 45 kg) are standing facing each other on a frozen pond. The son pushes on the father and finds himself moving backward at 3 after they have separated. How fast is the father moving?
*Tuesday, March 11, 2014 at 12:25pm*

**physics**

A friend is making an iMovie and wants your help designing a skateboard stunt. You estimate that your friend�s mass is four times greater than that of the skateboard. For the following questions, ignore friction. In one scenario, your friend starts by standing at rest ...
*Tuesday, March 11, 2014 at 12:24pm*

**physics**

Two air-track gliders are held together with a string. The mass of glider A is twice that of glider B. A spring is tightly compressed between the gliders. The gliders are initially at rest and the spring is released by burning the string. If glider B has a speed of 3 m/s after...
*Tuesday, March 11, 2014 at 12:19pm*

**physics**

A tennis ball (m= 0.2 kg) is thrown at a brick wall. It is traveling horizontally at 16 just before hitting the wall and rebounds from the wall at 8 , still traveling horizontally. The ball is in contact with the wall for 0.04 s. What is the magnitude of the average force of ...
*Tuesday, March 11, 2014 at 12:18pm*

**physics**

A 600-kg geosynchronous satellite has an orbital radius of 6.6 Earth radii. What gravitational force does Earth exert on the satellite? A. 13.8 N B. 90.9 N C. 138 N D. 909 N
*Tuesday, March 11, 2014 at 12:13pm*

**physics**

A solid lead sphere of radius 10 m (about 66 ft across!) has a mass of about 57 million kg. If two of these spheres are floating in deep space with their centers 20 m apart, the gravitational attraction between the spheres is only 540 N (about 120 lb). How large would this ...
*Tuesday, March 11, 2014 at 12:10pm*

**physics**

An ashtray slides across a table with a speed of 0.9 and falls off the edge. If it takes 0.4 s to reach the floor, how far from the edge of the table does the ashtray land?
*Tuesday, March 11, 2014 at 12:07pm*

**physics**

What is the change in velocity if a car traveling 30{m}/{s} north slows to 20{m}/{s} north? A. 20{m}/{s} north B. 10{m}/{s} north C. 30{m}/{s} south D. 10 {m}/{s} south
*Tuesday, March 11, 2014 at 12:04pm*

**physics 1**

A 64.4-kg skateboarder starts out with a speed of 1.95 m/s. He does 119 J of work on himself by pushing with his feet against the ground. In addition, friction does -260 J of work on him. In both cases, the forces doing the work are non-conservative. The final speed of the ...
*Tuesday, March 11, 2014 at 11:59am*

**physics 1**

The model airplane in Figure 5.6 is flying at a speed of 13.6 m/s on a horizontal circle of radius 19.1 m. The mass of the plane is 1.20 kg. The person holding the guideline pulls it in until the radius of the circle becomes 10.6 m. The plane speeds up, and the tension in the ...
*Tuesday, March 11, 2014 at 11:57am*

**physics**

A sled is being pulled across a horizontal patch of snow. Friction is negligible. The pulling force points in the same direction as the sled's displacement, which is along the +x axis. As a result, the kinetic energy of the sled increases by 47.5 percent. By what ...
*Tuesday, March 11, 2014 at 11:55am*

**Physics**

A 5.0-g bullet traveling horizontally at an unknown speed hits and embeds itself in a 0.195-kg block resting on a frictionless table. The block slides into and compresses a 180-N/m spring a distance of 0.15m before stopping the block and bullet. Determine the initial speed of ...
*Tuesday, March 11, 2014 at 11:46am*

**physics**

A pole-vaulter just clears the bar at 4.07 m and falls back to the ground. The change in the vaulter's potential energy during the fall is -3900 J. What is his weight?
*Tuesday, March 11, 2014 at 11:42am*

**Physics**

A solar sail is a possble means of interplanetary travel. It uses the pressure from the sun's light to provided a force on the sail (like a regular sailboat does with wind). If the force from the sun's light on the sail is equal to 4.1 Newtons, how fast will the '...
*Tuesday, March 11, 2014 at 11:42am*

**Physics**

How fast can a car be going around a turn with radius 42.3 m if the road is covered with ice? (The μs for rubber on ice is 0.10)? Give your answer in miles per hour.
*Tuesday, March 11, 2014 at 11:41am*

**Physics**

A car with a mass of 900 kg moves along a road at a 89 km/hour at equal speed. On the road is a curve with a radius of 250. a) What is the force in the curve between the tires and the road if the road is horizontal? b) What inclination is the best for that car on the road...
*Tuesday, March 11, 2014 at 11:24am*

**Physics**

1. A standard LP record has a diameter of 30 centimeters. A record on a standard turntable rotates 33.3 times a minute. What is the centripetal acceleration of a point on the edge of the record?(? m/s2) 2. If a 7.3 gram coin is placed at the very edge of the record described ...
*Tuesday, March 11, 2014 at 10:55am*

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