1. The speed needed at the bottom of a loop the loop track so that a car can coast to the top, with sufficient speed to stay on the track, depends on the mass of the car. (neglect the effects of friction)
a.) always true
b.) never true
c.) sometimes true, since kinetic energy is a function of mass
d.) sometimes true, since potential energy is a function of mass

2. A brick and a pebble fall from the roof of an apartment building under construction. At some point the brick is moving at a speed of 3m/s and the pebble's speed is 5m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?
a.) 25 to 9
b.) 5 to 3
c.) 12.5 to 4.5
d.) 3 to 5

Any help is appreciated, and no guessing please.