Question

A force $F=3x^2$, where x is the displacement, is applied on an object. The work done to move the object from x = 0 m to x = 5 m is units.

• A. 100
• B. 125
• C. 140
• D. 50

Answer 1

The correct option is B 125

We know that work done by force F is given by $W=\int Fdx$ , when the displacement x is in the direction of force.

Here, work done = $\int 3x^{2}dx$

$W\left(x\right)=x^3+C$

Work done when x= 0 is zero.

$\Rightarrow W\left(0\right)=0$

$\Rightarrow C=0$

We want to find W(5)

$W\left(5\right)=5^3$

= 125