Q. Force of 4 N is applied on a body of mass 20 kg. The work done in 3rd second is
A) 2 J
B) 4 J
C) 16 J
D) 1.2 J
Explanation
(a) Acceleration
$\ a = \frac{F}{m} = \frac{4}{20} = \frac{1}{5}{ms}^{- 2}$
Distance covered by body in 3rd second
$= \frac{1}{2} \times \frac{1}{5} \times (2 \times 3 - 1) = \frac{5}{10} = \frac{1}{2}m$
$\therefore\ \ W = 4 \times \frac{1}{2} = 2J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.