Question

A car of mass 1000 kg travelling at a speed of 72 km/h hits a tree and comes to rest in 0.2 s. The average force on the car during the impact is

• A. $ 36\times {{10}^{4}}N $
• B. $ 1\times {{10}^{5}}N $
• C. $ 36\times {{10}^{7}}N $
• D. $ 36\times {{10}^{5}}N $

Answer 1

Answer: (B)

Given, $ m=1000\,\,kg,\,\,v=72\,\,km/h $ and $ \Delta t=0.2\,\,s $ $ \therefore $ $ {{F}_{av}}=\frac{m{{v}_{av}}}{\Delta t} $ $ =\frac{1000\times 20\times 10}{0.2} $ $ =1\times {{10}^{5}}N $