Question

A $1\text{kg}$ body is sliding up an inclined plane of inclination ${30}^{\circ }$. Find the work done by the force of gravity in moving the body through $1\text{m}$.

• A. $5\text{J}$
• B. $-5\text{J}$
• C. $10\text{J}$
• D. $-10\text{J}$

Answer 1

The correct option is B $-5\text{J}$



We know that, $W=\overrightarrow{F}.\overrightarrow{d}$

$\Rightarrow W=Fd\cos \theta =mgd\cos \theta$

$\Rightarrow W=1\times 10\times 1\times \cos {120}^{\circ }=-5\text{J}$