Question

Two figures are shown above that are related to the concept of work. Which of the following statements is correct related to the work done by the force F in these figures?

• A. In figure (a), work done is zero
• B. In figure (a), work done is positive while in figure (b), work done is negative.
• C. In figure (a), work done is negative while in figure (b), work done is positive.
• D. In figure (b), work done is zero.

Answer 1

The correct option is D In figure (b), work done is zero.

In fig.a man is holding inclined so,the angle between displacement and force is less than ${90}^0$in fig.b man is holding the object perpendicularly,so the angle between displacement and force is ${90}^0$.
we know
$W=F\times S\times cos\theta$
for fig.(a)
$\theta =lessthan{90}^0;cos\left(0^{0}to{90}^0\right)=\left(0to1\right);so,Workdonewillbepositive$.
for fig.(b)
$\theta ={90}^0;cos{90}^0=0;so,Workdonewillbezero$.