Question

What would be the work ( positive, negative or zero) when it is done against gravity. Explain your answer with a diagram.

Answer 1

Dear Student
Since, work done is given by :-
W = $\underset{F}{\to }.\underset{s}{\to }$ = ( F cosθ ) s
When a body is thrown up, its motion is opposed by gravity. The angle θ between gravitational force $\underset{F}{\to }$ and the displacement $\underset{s}{\to }$ is 180⁰. As cos ​θ = cos 180⁰ = -1. Therefore, work done by a gravity on a body moving upwards is negative.
Regards