Question

A force of $7N$ action an object. The displacement is $8m$, in the direction of the force. Consider forces acting on the object through displacement. What is the work done in this case?
A. $96J$
B. $56J$
C. $76J$
D. $156J$

Answer 1

In Physics, work is said to be done only when there is displacement on applying force. No matter how hard you push the wall but because there is no displacement no work is done by you according to Physics. Here, we will discuss the relationship between work, force, and displacement.

Complete step by step solution:
Let us first write the information given in the question.
Force = $7N$, displacement = $8m$.
We have to calculate the work in displacing the object.
The formula to calculate the work done when force and displacement are known is given below.
$W = \vec F.\vec d = Fd\cos \theta$
As it is given that the force is acting in the direction of displacement. So, the angle will be zero.
Let us substitute the values in the above formula.
$W = \left( 7 \right)\left( 8 \right)\cos 0$
On further simplifying the above expression we get the following work done.
$W = 56J$
Hence, the work done in displacing the object by $8m$ is $56J$.
Hence, the correct option is (B) $56J$.

Note:
So, to solve the numerical based on work done you have to first see whether there is displacement happening, if not then work done will be zero.
When displacement is happening then you have to find the angle force is making with the displacement.
When force and displacement are perpendicular to each other, the cosine of $90$ will be zero. And again work done in this case will be zero.