A student rolls two marbles down an inclined plane. One marble has a
mass of 4.8 grams. The student calculates its kinetic energy to be
0.0035 Joules when it reaches the end of the plane. The second
marble has a mass of 2.4 grams. What is the best prediction for its
kinetic energy at the end of the plane? (1 point)
0.014 J
0.007 J
0.00175 J
0.0035 J
Since kinetic energy is directly proportional to the mass of an object, the best prediction for the second marble's kinetic energy at the end of the plane would be 0.00175 J.
This is obtained by halving the mass of the first marble (2.4 grams = half of 4.8 grams) and therefore, halving its kinetic energy as well (0.0035 J = half of 0.007 J).
Ke at bottom = Pe at top = m g h
g h is the same but m is half so Pe is half so Ke is half
0.0035 / = 0.00175 Joules