Mixed Review

Energy & Momentum

  1. A 150-g baseball reaches a batter with a speed of 25 m/s. After it has been struck, it leaves the bat at 35 m/s in the opposite direction. If the ball was in contact with the bat for .001 s, find the average force exerted on it during this period. (9 kN)
  1. A 30.0 kg girl who is running at 3.0 m/s jumps on a stationary 10.0 kg sled on a frozen lake. How fast does the sled then move? (2.3 m/s)
  1. A 0.5 kg stone moving north at 4 m/s collides with a 4 kg lump of clay moving west at 1 m/s. The stone becomes embedded in the clay. What is the velocity of the composite body after the collision? (1 m/s)
  1. A 1.0 kg block, starting from 5.0 m high slides without friction down the slope as shown. At the bottom, it collides inelastically with a 5.0 kg block that is initially at rest. To what height (h) will the two block combo slide up the slope? (0.14m)
  1. A 0.500-kg bullet traveling at 300. m/s hits a 5.0 kg block of wood and becomes imbedded in the block. The block then slides without friction into a spring. If the spring is compressed .25 m, calculate its spring constant. (65,000 N/m)
  1. A 20.0 kg block moving at 5.0 m/s hits a stationary 5.0 kg bock. The stick together and hit a spring with a spring constant of 200. N/m. How far is the spring compressed? (1.4 m)
  1. A 5.0 kg football hits is caught by a 55 kg kid. Knocked off balanced by the catch, the kid then falls and slides down a frictionless 1.0 m tall hill. At the bottom of the hill, the kid slides 1.4 m on the pavement, where the coefficient of kinetic friction is 0.75. How fast was the football initially thrown? (12m/s)
  1. A 20. kg crate at rest on a 10. m high ramp, requires a 100. J push to get it moving down the ramp. The ramp and crate experience 20. J of friction. What is the kinetic energy of the block at the bottom of the ramp? (2.0x103J)
  1. A worker pulls a 40.0-kg crate with a rope at the 30.0o angle to the horizontal. The coefficient of sliding friction between the crate and the floor is 0.55. If he moves the crate with a constant velocity a distance of 7.00 m, how much work does the worker do on the crate? (1150J)
  1. A 35 g superball hits a wall at 10.0 m/s. If bounces off the wall with a speed of 8.0 m/s and the ball is in contact with the wall for 0.20 s, what is the average force exerted by the wall on the ball? (3.2 N)
  1. A 2.5 kg block starts from rest at an initial height of 35 cm and slides down a frictionless circular ramp. It slides for 83 cm on a horizontal friction-filled surface before coming to a stop. What is the coefficient of kinetic friction? (0.42)
  1. A 70. kg skier is pulled 60. m up a 30. degree frictionless slope at 2.0 m/s. How much work is done & what is power of the motor? (21,000 J; 690 W)