I know there is no not force on the person, but are they moving at the velocity of the car or are they at rest?
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The person is moving at the same velocity as the car.
Example:
When a car goes really fast, and does a sudden stop, don't you move forward from your seat? That's one reason for a seatbelt. If you were at rest, you wouldn't move forward. It was because you were at motion with the car, and it did a sudden stop, therefore you leaned forward and ended up stopping with the vehicle.
Example:
When a car goes really fast, and does a sudden stop, don't you move forward from your seat? That's one reason for a seatbelt. If you were at rest, you wouldn't move forward. It was because you were at motion with the car, and it did a sudden stop, therefore you leaned forward and ended up stopping with the vehicle.
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Velocity is relative, which means you must cite the reference point for it to be meaningful.
In this case let Uc/g = speed of car wrt ground, Vp/c = speed of person wrt to car; so Wp/g = Uc/g + Vp/c = speed of person wrt ground.
EXAMPLE: Uc/g = 120 kph is your Lamborghini on the autostrada, Vp/c = 0 kph is you sitting behind its steering wheel about to shove it into high gear; so Wp/g = Uc/g + Vp/c = 120 + 0 = 120 kph. You are moving at a constant 120 kph wrt ground even though you're not movng wrt the steering wheel.
In this case let Uc/g = speed of car wrt ground, Vp/c = speed of person wrt to car; so Wp/g = Uc/g + Vp/c = speed of person wrt ground.
EXAMPLE: Uc/g = 120 kph is your Lamborghini on the autostrada, Vp/c = 0 kph is you sitting behind its steering wheel about to shove it into high gear; so Wp/g = Uc/g + Vp/c = 120 + 0 = 120 kph. You are moving at a constant 120 kph wrt ground even though you're not movng wrt the steering wheel.
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He has the same velocity of the car with respect to an object standing outside of the car. but he is at rest ( velocity = 0) with respect to the car itself or an object in the car. So it all depends on the perspective.