Mechanics | Relativity Answers

A 0.5 kg ball traveling at 6 m/s collides with a 1-kg ball that was moving in the opposite direction at 12 m/s. The 0.5-kg ball moves away at 14 m/s in the opposite direction after the collision. Find the velocity of the 1-kg ball after the collision.

a 25 kg child sits in a swing that is attached to ropes 1.5 m long. It is 0.5m above the ground. Find the potential energy of the child relative to his lowest position when the ropes are (a) horizontal, (b) vertical ; (c) make 30 degrees with the horizontal.

Find the center of the mass of four 2 kg bodies placed at each corner of a square of side 1.5 m. Show the given, required, equations, solutions and answer.

Kyle is driving his car at 15 m/s when he noticed that he is approaching a stalled truck that is approximately 35m away . He steps on the brakes and the car stops 1.0 m away from the stalled truck . At what rate did the car slow down ? Assume that Kyle's reaction time is 2.0s . Reaction time is the time for a person to notice , think and act in response to a given situation .

A block of mass 2.25 kg starts out at rest at the top of a 15.0 m long plane inclined 30 degrees with the horizontal. (a) What is its initial gravitational potential energy? As it slides down the plane, the block encounters a frictional force of 3.5 N. (b) How much work is done to overcome friction? (c) What is the kinetic energy of the block when it reaches the bottom of the incline? At a distance of 0.5 m from the bottom of the inclined plane is a horizontal spring force constant 52 N/m. Suppose that the coefficient of kinetic friction between the block and the horizontal surface is 0.15. (d) What is the kinetic energy of the block just before it comes in contact with the spring? (e) By how much will the spring be compressed? (f) What is the work done against friction as the block moves along the horizontal surface?

A 1.25 kg ball is projected vertically upward from the ground with an initial speed of 5.6 m/s. How high will it rise? What is its speed when it is at half of its maximum height? Use conservation of mechanical energy to solve this problem. Show the given, required, equations, solution and answer.

5. A sled is pulled by a large work horse. The sled has a mass of 1500kg and the horse pulls with 2500N. If the coefficient of friction is 0.1 determine the acceleration.

A box has a weight of 5000N. If the coefficient of static friction is 0.8 and the coefficient of kinetic friction is 0.5. How much force is required to get the box to start moving? How much is required to move the box at a constant velocity?

Your boss has asked you to move some boxes in a warehouse. In each box is a refrigerator that has a mass of 80kg. a) If the µs is 0.25 would you be able to move the box with a force of 180N? b) What is the minimum force required to make the boxes move? c) What would be the required coefficient of friction in order to move the boxes with a constant velocity if the applied force was 100N?

James pulls a sled with a mass of 80kg across his lawn. He pulls with 150N of force. a) Determine the force of friction if the acceleration is 0.5m/s2. b) What is the coefficient of friction?