Question

Trucks 1 and 2 are traveling at the same constant velocity but truck 1's energy due to motion is two times less than that of truck 2. This is because Truck 1's mass is:

Answer 1

Kinetic energy = 0.5 * m * v²

m mass
v velocity

If the velocity stays the same and the kinetic energy goes down by a factor of 2, the mass must go down by a factor of 2 also.