I am a bit confuse about gravity and work
Suppose a ball falls from one height to another, hi to hf
When talking about the system BE the ball AND the earth, all the work done is internal, and no external work, change in KE = change in PE, right?
But when talking about the system B of just...
Quick question about net external work
Got a block (A) attach to Spring which attach to a Wall
Hand pushes A toward the wall which compress the Spring
So hand is doing positive work on A, W = F*D, work is whatever force by hand times distance..
But work done ON the spring BY the wall is...