Question

A man holding 7N weight moves 7m horizontal and 5m vertical , find the work done

Answer 1

Answer:

35 J

Explanation:

The man is holding the box: this means that he is applying a force vertically upward, to balance the weight of the box (which pushes downward).

Therefore, we can ignore the horizontal displacement of the man, because the force applied (vertically upward) is perpendicular to that displacement (horizontal), so the work done for that is zero.

So, only the vertical motion contributes to the work. The work done by the man is equal to the gain in gravitational potential energy of the box, so:

$W=(mg)\Delta h$

where

$mg=7 N$ is the weight of the box

$\Delta h=5 m$ is the vertical displacement

Substituting, we find

$W=(7N)(5 m)=35 J$