Question

Which of the following statements are true for Work?

Answer 1

1)If the work done on an object by a force is zero, then either the force or the displacement must have zero magnitude.

2)Two objects with unequal mass are released from rest from the same height. They slide without friction down a slope and then encounter a rough horizontal region. The coefficient of kinetic friction in the rough region is the same for both masses. The lighter mass will travel further along the rough region before stopping.

3)The formula W = F·d·cosθ can be used only if the force is constant over the distance d.

4)If a force acts downwards, it does negative work.

5) Two balls with different masses reach the same height when shot into the air from the ground. If there is no air drag, both balls must have left the ground with the same speed.

Answer 2

I don't remember for the 3rd statement, but I think 1, 2, and 5 are true.