here are a few physics questions i need help?

Question

A bowling ball rolls to the left and a ball of putty tolls to the right. The two collide and ball of putty sticks to the bowling ball, which now rolls slower, to the left. What was not conserved in the collision?
      A. mass of the bowling ball
      B.mass of the putty ball
      C.momentum of the system
      D.kinetic energy of the system

A rock falls from the top of the builidng. It feels a downward .force of 9 N and an upward force of 5 N due to air resistance. Which statement is true about the rock/s momentum?
  A. it is constant
  B. it is conserved
  C. it is changing
  D. it is negative

3. A roller coaster with mass m dives down a hill  with height h and has a velocity v at the bottom of the hill. When does the roller have the most total energy?
a. at the top of the hill
b.halfway down the hill
c.at the bottom of the hill
d. always has the same total energy

120 · Accepted Answer

1. D.  Kinetic energy in a inelastic collision is not conserved.

2. C.  Since there is force acting on it, it provides acceleration, so the velocity must be increasing.  Momentum=mass * velocity.  So the momentum is changing.

3.  D.  It always have the same total energy.  Whenever it's potential energy decreases, it would be made up by its increase in kinetic energy.

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here are a few physics questions i need help?

1 Answer