Sunday

September 21, 2014

September 21, 2014

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**Chemistry**

The net reaction for fusion on a star like our Sun is: 4H(1,1) ==> He(4,2) + 2e(0,+1) Calculate the mass defect for this reaction. If one atom of He is formed this way, calculate the energy released. If one Kg of He is formed, calculate the energy released. The masses of ...
*Sunday, March 16, 2014 at 12:07pm*

**Physics**

A .75kg block is going at a velocity of 1.5m/s and moves on a frictionless surface. Then all of a sudden, the block hits a rough patch. The rough patch is .5m long and has a coefficient of friction of .25. Then it slides onto the frictionless surface again. The mass then ...
*Sunday, March 16, 2014 at 11:34am*

**Physics**

A man wishes to cross a river from A to B, a distance of 800m. He can row at 8km per hour, in what direction should he head the boat to travel directly from A to B? How long does it take him to reach B? Please show working. Thank You!
*Sunday, March 16, 2014 at 10:06am*

**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/...
*Saturday, March 15, 2014 at 11:16pm*

**Physics**

torque to move a block of m=200kg for 10m at an angle of 25 degree with a speed of 20m/s.
*Saturday, March 15, 2014 at 9:20pm*

**Physics**

A 49.5-kg skater is traveling due east at a speed of 2.88 m/s. A 72.5-kg skater is moving due south at a speed of 6.82 m/s. They collide and hold on to each other after the collision, managing to move off at an angle south of east, with a speed of vf. (a) Find the angle. (b) ...
*Saturday, March 15, 2014 at 6:04pm*

**physics**

A 12.0 g bullet is fired into a 13.9kg wooden block that is hanging straight down, suspended by a 2.00 m length of light line. The bullet has a muzzle velocity of 94.2 m/s. When the bullet hits the block, the bullet stays in the block. The block swings outward so that the line...
*Saturday, March 15, 2014 at 6:01pm*

**Physics**

The Achilles tendon is attached to the rear of the foot. Assume that a person has a mass of 53 kg and that D is twice as long as d. When a person elevates himself just barely off the floor on the "ball of one foot," estimate the tension in the Achilles tendon (...
*Saturday, March 15, 2014 at 5:58pm*

**physics**

(a) Suppose a hockey puck slides down a frictionless ramp with an acceleration of 5.60 m/s2. What angle does the ramp make with respect to the horizontal?
*Saturday, March 15, 2014 at 5:14pm*

**Physics**

Suppose the hand in holds a 20 kg mass . What force, FM, is required of the deltoid muscle? Assume the mass is 50 cm from the shoulder joint, the force of tension in the deltoid is directed 15° to the horizontal, and the mass of the arm alone is 3.8 kg.
*Saturday, March 15, 2014 at 5:07pm*

**Physics**

A block of mass 2.48 kg is kept at rest as it compresses a horizontal massless spring (k= 113 N/m) by 4.65 cm. As the block is released, it travels 0.462 m on a rough horizontal surface before stopping. The acceleration of gravity is 9.8 m/s^2. Calculate the coefficient of ...
*Saturday, March 15, 2014 at 4:41pm*

**Physics**

1. A 3 kg block collides with a massless spring of spring constant 90 N/m attached to a wall. The speed of the block was observed to be 1.5 m/s at the moment of collision. The acceleration of gravity is 9.8 m/s^2. How far does the spring compress if the surface on which the ...
*Saturday, March 15, 2014 at 4:39pm*

**Physics**

A racing car has a mass of 1530 kg. The acceleration of gravity is 9.8 m/s^2. What is its kinetic energy if it has a speed of 136 km/h? Answer in units of J.
*Saturday, March 15, 2014 at 4:22pm*

**Physics**

Shawn and his bike have a total mass of 58.5 kg. Shawn rides his bike 0.54 km in 17.2 min at a constant velocity. The acceleration of gravity is 9.8 m/s^2. What is Shawn’s kinetic energy? Answer in units of J.
*Saturday, March 15, 2014 at 4:20pm*

**Physics**

A team of dogs drags a 151 kg sled 0.863 km over a horizontal surface at a constant speed. The coefficient of friction between the sled and the snow is 0.223.The acceleration of gravity is 9.8 m/s^2. 1. Find the work done by the dogs. Answer in units of kJ. 2. Find the energy ...
*Saturday, March 15, 2014 at 4:18pm*

**Physics**

A cart loaded with bricks has a total mass of 22.3 kg and is pulled at constant speed by a rope. The rope is inclined at 27.3◦ degrees above the horizontal and the cart moves 9.3 m on a horizontal surface. The coefficient of kinetic friction between ground and cart is 0....
*Saturday, March 15, 2014 at 4:15pm*

**Physics**

A uniform ladder of mass m = 6.5 kg and length l = 2.1 m leans at an angle against a frictionless wall, Fig. 12-72. If the coefficient of static friction between the ladder and the ground is µs = 0.3, what is the minimum angle at which the ladder will not slip?
*Saturday, March 15, 2014 at 3:51pm*

**Physics**

A toy gun uses a spring to project a 6.1 g soft rubber sphere horizontally. The spring constant is 12.0 N/m, the barrel of the gun is 12.6 cm long, and a constant frictional force of 0.031 N exists between barrel and projectile. With what speed does the projectile leave the ...
*Saturday, March 15, 2014 at 10:41am*

**Physics**

A car of mass 1900kgs accelerates from rest to a speed of 27ms-1 in 8.1s.Calculate the average rate at which kinetic energy is supplied to the car during the acceleration.
*Saturday, March 15, 2014 at 8:28am*

**physics**

1) a bullet of mass 0.02 kg is fired into a block of wood of mass 1.5 kg resting on a horizontal table. The block moves offwith an initial speed of 8 m/s. Estimate the speed with the bullet strikes the block. 2) The bullet in question 1 is fired from a rifle of mass 2.5 kg. ...
*Saturday, March 15, 2014 at 3:40am*

**physics**

A ball of mass 0.1 kg is dropped from a height of 2 m onto a hard surface. If rebounds to a height of 1.5 m and it is in contact with the surface for 0.05s. Calculate the: (a) speed with which it strikes the surface. (b) speed with which it leaves the surface. (c) change in ...
*Saturday, March 15, 2014 at 3:29am*

**physics**

1)when a person stands on bathroom scales the scale reads 60 kg. Suppose the person stands on the same scales when in an elevator (lift). the elevator accelerates upwards at 2m/s2. Determine the new reading on the scale. 2)When a golfer strikes a golf ball it is in contact ...
*Saturday, March 15, 2014 at 3:22am*

**physics**

An object of weight 50 N is suspended vertically by two strings. The strings are of the same lenght and the angle between them is 60 degree. Draw a free body diagram of the forces acting on the object. Calculate the tension in the strings.
*Saturday, March 15, 2014 at 3:13am*

**physics**

A 3 kg mass attached to a string 6 m long is to be swung in a circular at a constant speed making one complete revolution in 1.25 s. Determine the value that the breaking strain that the string must not exceed if the string is not to break when the circular motion is in (a) a ...
*Saturday, March 15, 2014 at 3:03am*

**physics**

A missile of mass 1.20 102 kg is fired from a plane of mass 5.50 103 kg initially moving at a speed of 3.05 102 m/s. If the speed of the missile relative to the plane is 1.21 103 m/s, what is the final velocity of the plane?
*Friday, March 14, 2014 at 9:45pm*

**physics**

Two cars approach an ice-covered intersection. One car, of mass 1.26 103 kg, is initially traveling north at 10.6 m/s. The other car, of mass 1.66 103 kg, is initially traveling east at 10.6 m/s. The cars reach the intersection at the same instant, collide, and move off ...
*Friday, March 14, 2014 at 9:44pm*

**physics**

A 70 kg man stands on an accurate spring scale inside the elevator. Given that the lift can accelerate and decelerate at 2.2 m/s^2, Compute the man's maximum and minimum weight.
*Friday, March 14, 2014 at 9:29pm*

**physics**

An astronaut shoots you in space given that the bullet is weightless, could it injure you?
*Friday, March 14, 2014 at 9:22pm*

**physics**

Calculate the force needed to accelerate a 1 kg ball by 3 m/s: a. in space along way from the earth. b. on the ground in a direction horizontal to the ground. c. on the earth vertically upward.
*Friday, March 14, 2014 at 9:19pm*

**physics**

Describe the difference between the quantities, mass and weight. Give a description of two distinctly different ways in which object's weight can be altered.
*Friday, March 14, 2014 at 9:13pm*

**physics**

A 200 kg piano is suspended by a rope from a high building. (Assume the mass of the rope is zero). a. What is the weight of the piano? b. What is the tension of the rope? c. The piano is now hoisted up with an initial acceleration of 1 m/s. What is the minimum value of the ...
*Friday, March 14, 2014 at 9:10pm*

**physics**

A five kg box is pulled along a frictionless surface by a string just capable of suspending a 15 kg mass at rest. What is the maximum acceleration that can be given to the box?
*Friday, March 14, 2014 at 9:06pm*

**physics**

A jet fighter with mass 5000 kg accelerates from 360 km/hr in 10b s. Compute the minimum thrust required by the jet's engines.
*Friday, March 14, 2014 at 9:03pm*

**physics**

A 60 kg of sprinter accelerates from rest at 2.5 m?s^2 East for 4s. What force is acting and what is the final speed?
*Friday, March 14, 2014 at 9:00pm*

**physics**

A 10^4 kg train moving at 20m/s stops in a distance of 500m. Calculate the force applied by the train's braking system.
*Friday, March 14, 2014 at 8:56pm*

**physics**

When rolling along the felt on the billiard table, the ball experiences a frictional force of 0.2 N. a. What is the deceleration of the ball on the felt? b. How far will the ball roll before stopping? c. Explain this in terms of Newtons first law of motion.
*Friday, March 14, 2014 at 8:52pm*

**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**

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**

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**

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**

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*

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