Question

In which situation is no work being done? A. a person carrying a box from one place to another B. a person picking up a box from the ground C. a person pushing a box from one place to another D. a person pulling a box from one place to another

Answer 1

Answer:

A person carrying a box from one place to another.

Explanation:

The work done is defined as the product of force, displacement and the angle between the force and displacement. Mathematically, it can be written as :

$W=F.d$

$W=Fd\ cos\ \theta$

Where

$\theta$ is the angle between the force and the displacement

When $\theta=90^0$, then W = 0 (since, cos 90 = 0)

The situation in which no work being done is (a) " a person carrying a box from one place to another". In this case, the force acting on the person is gravitational force only which acts in downward direction and the person is carrying box from one place to another. So, the angle between the force and displacement is 90 degrees. Hence, no work being done.

Answer 2

Picking up a box, pushing a box along the ground, and pulling a box along the ground (B, C, and D) definitely involve work being done.

If a person CARRIES a box from one place to another, AND keeps it at the same height during the entire carry, then no work is done. ( A )