Question

A truck is moving at 15m/s when the brakes are applied, in order to come to a stop before hitting a pothole 20m ahead. In the back of the truck is a crate. It is not tied down, but has a coefficient of static friction µs = 0.4 with the truck bed. Will the truck be able to stop in time, without the crate sliding?

Please explain how you got the answer, like step by step. I don't want just the answer, I want to understand how to get to it (understand the concept). Thank you in advance.

Answer 1

In this problem we have been given that the pothole is 20 metres away that means we have to stop the truck within the distance of 20 metre. In order to do so we will be applying the brakes. once the brakes have been applied it will create a pseudo force acting on the crate which is put on the back of the truck and this pseudo force will try to move or shift the crate. the question arises whether the frictional force acting between the crate and the surface of the truck is greater than the pseudo force which will try to move it or not. if the friction force is not sufficient or the pseudo force is more than the friction force then the great will slide.

So to do this problem we have to compare the pseudo force with the friction force. Pseudo force can be calculated by first calculating the deceleration of the truck required to stop within 20 meter distance.