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

  • Welcome to Motor Vehicle Maintenance & Repair! If you could do us a favor and let us know exactly what you're trying to do or prove, it would go a long way to helping you. Can you post the theorem itself and an example of how it might be used? Show us you've done a little homework and we might be able to help you. – Pᴀᴜʟsᴛᴇʀ2 Dec 28 '17 at 16:02
  • Mass * velocity squared compared to maximum force from braking, wheel friction etc – Solar Mike Dec 28 '17 at 19:04
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    I'm voting to close this question as off-topic because it's really a physics question. In real life there is a relationship, sure, but it is not practically useful as there are so many other variables. – Rory Alsop Dec 28 '17 at 19:24

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.

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