Atrain with a mass of 25000 kg increases it’s speed from 10 m/s to 25 m/s in 20 seconds. assume that the acceleration is constant and that you can neglect friction
what is the acceleration of the train

Bone-strengthening physical activity done increases bone-mineral content and bone density in youth.

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?

The energy equivalent of the rest mass of an electron is