Question

A car whose total mass is 800kg travelling with a uniform velocity of 20m/s suddenly observes a stationary dog on it's path 50m ahead. If the total force applied on the breaking system on the car by the driver is 2000N what would most probably happen

Answer 1

Answer:

Driver hits the dog

Explanation:

From kinematics equation

$v_f^{2}=v_i^{2}+2as$ and making a the subject

$a=\frac {v_f^{2}-v_i^{2}}{2s}=\frac {0-20^{2}}{2*50}=-4m/s^{2}$

F=ma=800*-4=-3200  N

The driver is required to apply a force of 3200 N to effectively not hit the dog. However, when the driver applies 2000 N, this is less the required force by 1200 N hence the driver hits the dog.