The total momentum of a system of objects is conserved when there is no external, unbalanced force on the system.

Why does the input force have to be greater than the force needed to lift the bale?

Distinguish between a transverse wave and a longitudinal wave.

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.