Momentum of a Car: What Happens When Stopping?

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Discussion Overview

The discussion revolves around the concept of momentum in the context of a car coming to a stop. Participants explore the implications of forces acting on the car, the definition of momentum, and the conservation of momentum in different scenarios.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant states that forces acting on the car do work to slow it down, implying that momentum is not conserved in this process.
  • Another participant argues that the momentum should be zero when the car stops, as momentum is defined as mass in motion.
  • A different perspective suggests that in an isolated system, momentum is conserved, and when the car brakes to a stop, its momentum is transferred to the Earth, although the Earth's change is negligible due to its large mass.

Areas of Agreement / Disagreement

Participants express differing views on whether momentum is conserved when a car stops, with some asserting it is not conserved due to external forces, while others argue for conservation in an isolated system.

Contextual Notes

There are unresolved assumptions regarding the definition of the system in question and the conditions under which momentum conservation is considered.

mprm86
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What happens to the momentum of a car in movement when it stops?
 
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The car has forces acting on it to slow it down, they all do work on the car, and the energy is transferred through the air resistance and friction.

Momentum isn't conserved, if that's what your asking.
 
it should be 0 because the velocity becomes 0 when the car stops. (Momentum is mass in motion)
 
mprm86 said:
What happens to the momentum of a car in movement when it stops?
In an isolated system, momentum is conserved. The momentum of the car when it brakes to a stop, is transferred to the earth. But the Earth's mass is so much larger than the car's that the Earth's change in rotation speed is not measurable.
 

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