Q. A body moves a distance of 10 m along a straight line under action of 5 N force. If work done is 25 J, then angle between the force and direction of motion of the body will be
A) $75^{0}$
B) $60^{0\ }$
C) $45^{0\ }$
D) $30^{0\ }$
Explanation
(b) Given $W = 25\ J,F = 5\ N,\mathrm{\Delta}s = 10m$
Work=Force$\times displacement$
$W = (F\cos\theta) \times \mathrm{\Delta}s$
Or $\cos\theta$=$\frac{W}{F \bullet \mathrm{\Delta}s}$
Or $\cos{\theta = \frac{25}{5 \times 10}} = \frac{1}{2}or\ \theta = \cos^{- 1}{\left( \frac{1}{2} \right) = 60{^\circ}}$
Hence, angle between force and direction of body is $60{^\circ}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.