1. A 37.5 N force drags an 7.50 kg block by a rope which makes an angle of 40 with a rough horizontal surface (uk = 0.400). The block starts from rest and is dragged a distance of 22.5 m in 7.50 s. a) what work is done by the applied force? B) What work is done by the friction force? C) what is the total (net) work done? D) What is the power expended by the total work? E) what is the final velocity of the block?
2. A 15 kg load of bricks hangs from one end of a rope that passes over a small, frictionless pulley. A 25 kg counterweight is suspended from the other end of the rope. The system is released from rest. A) what is the acceleration of the system? B) What is the tension in the rope while the load is moving?
3. A 2.50 kg block is started down a rough inclined plane with an initial velocity of 2.75 m/s. The plane is 4 m long and makes an angle of 35 degree with the horizontal. If the block comes to rest at the bottom of the plane, find ( with respect to the bottom of the plane): a) its total mechanical energy at the top, b) its total mechanical; energy at the bottom, c) the energy lost due to friction, and, d) the coefficient of friction between the block and the surface.
4. A baseball player throws a ball at an angle of 53.1 degree above the horizontal with an initial speed of 45 m/s. Find: a) the velocity of the ball and two times when the ball is at a height of 25 m above the point from which it was thrown. B) the horizontal distance the ball travels when it caught by another player, c) the velocity of the ball when it returns to the level from which it was thrown.
5. A 6 g bullet is fired horizontally into a 1.350 kg wooden block resting on a horizontal surface. The coefficient of kinetic friction between the block and surface is 0.345. The bullet remains imbedded in the block which is observed to slide 0.250 m along the surface before coming to rest. A) what was the initial speed of the bullet? B) how much mechanical energy is lost in the collision? C) what happened to the lost energy?
6. A 10.8 kg long cylindrical pulley is 1.25 m in radius and is pivoted on a horizontal axis at the top of a well. A rope is wrapped around the pulley and a 12.5 kg bucket of water is hung on the rope and released from rest. If the bucket falls 10 m to the water. A) the tension in the rope while the bucket is falling. B) the speed of the bucket when it strikes the water. C) the time it takes for the bucket to strike the water.
7. A uniform beam of 6 m length and 300 n weight supports a 400 n load as shown below. Determine the tension in the supporting wire and the force exerted by the pivot on the beam.
