Answer to Question #263159 in Mechanics | Relativity for Riwaydo Odorosh

Question

A high-performance car initially travelling 97.2 km/h came to a stop in just 2.9 s. The mass of the car and its contents was 1850 kg. What was the magnitude of the average net force (braking force) on the car while it decelerated?

1.7 x 10⁴N

4.9 x 10⁴N

1.8x 10⁴N

5.9 x 10⁴N

Answer 1

Explanations & Calculations

$\qquad\qquad \begin{aligned} \small \Sigma F&=\small ma\\ \small f&=\small 1850\,kg\times\Big(\frac{v-u}{t}\Big)\\ &=\small 1850\,kg\times\Big(\frac{0-27ms^{-1}}{2.9\,s}\Big)\\ &=\small -17224.1\,N\\ \small |f|&=\small 1.7\times10^4\,N \end{aligned}$

• Hence the answer is the first one.