- #1
Karagoz
In the picture above, there are three balls in separated small elevators. Elevator A lifts the ball upwards, elevator B stays still, elevator C moves the ball downwards, all in constant speed. (And this is a model, a simplification of the reality, we assume no other forces on the balls other than gravity force downwards and normal force upwards).
Since there's no acceleration, only constant speed or staying still, sum of the forces on the ball is 0 in both A, B and C.
But lifting the ball upwards requires more energy than keeping the ball still. But how is it that sum of the forces on the ball is equal (and zero) both in A, B and C?
If you have a force meter, and hang a 1KG object on it. Won't the force meter show higher value when you move the force meter (with the 1KG object hang on it) upwards in constant speed, than when you keep it still?