If kinetic energy is conserved by the apparatus shown in this ...

[james0929]

If kinetic energy is conserved by the apparatus shown in this figure, why do we find in class demonstrations that the balls eventually come to rest?
 a. Because the commercial versions of this apparatus are not built to exact specifications.
  b. Total energy, not kinetic energy, is conserved; the rest of the energy going to heat; but the heat loss in this experiment is normally ignored since it occurs very slowly.
  c. Because as some of the balls come to rest, others speed up.
  d. Because a hidden battery supplies the energy to keep the balls moving, and eventually runs out of energy.
  e. Total energy but not kinetic energy is conserved, the rest of the energy going to heat; but the device transforms the thermal energy back to kinetic energy.

Question 2

The unit for kinetic energy is the:
 a. impulse.
  b. newton.
  c. joule.
  d. watt.
  e. kilogram.

[spencer.martell]

Answer to Question 1

b

Answer to Question 2

c