IMPULSE Momentum theorem and stopping time of a car

Question

Can we apply impulse momentum theorem for calculating stopping time of car?

Answer 1

Well, 2 things:

1. momentum is always conserved in collisions. It's useless unless you are hitting something.
2. Impulse, we can do something with.

Impulse is 2 things:

• change in momentum
• force * interaction_time

If we are talking about stopping a car, then we presumable know the mass and velocity of the car while it is moving, therefore we can calculate it's initial momentum. Since we will be stopping the car, the final momentum will be zero, and therefore the change in momentum (the impulse) will be the initial momentum of the car (minus zero). If you know force (braking, drag and friction), divide the impulse by the force and you will get time.