Q. A vehicle of mass 120 kg is moving with a uniform velocity of 108$\ kmh^{- 1}$. The force required to step the vehicle in 10 s is
A) 90 N
B) 180 N
C) 360 N
D) 720 N
Explanation
(c) $v = 108 \times \frac{5}{18}ms^{- 1} = 30\ ms^{- 1}$
Momentum = 120$\times 30$ kg $ms^{- 1}$ (initial)
Final momentum = 0
Force $= \frac{Change\ in\ momentum}{Time}$
$= \frac{120 \times 30}{20} = 360$ N
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.