Direction of Momentum Problem

[baseballer]

Homework Statement

A) You travel north down a road in a car at constant velocity. In which direction (N, S, E, W, up, down) does the angular momentum vector point for one of the tires.

B) Same situation. If you slam on the brakes in which direction does the angular acceleration vector point for one of the tires. (N, S, E, W, up, down)

Homework Equations

L = r x p

The Attempt at a Solution

For A, I think it's East because of the right hand rule. My fingers would be curling forward and my thumb would be pointing to the Left.

For B, I'm not sure. I guess it would be West just because acceleration would be negative and in the opposite direction of A.

 

[Doc Al]

For A, I think it's East because of the right hand rule. My fingers would be curling forward and my thumb would be pointing to the Left.

You think left is East?

 

[baseballer]

Sorry about that. I meant West for A and East for B

 

[Doc Al]

Sorry about that. I meant West for A and East for B

Sounds good to me.

 

[HalfLostAndSearching]

But I'm not completely confident in that answer.

Your answer for A is correct. The angular momentum vector for one of the tires would point in the East direction.

For B, you are correct in thinking that the angular acceleration vector would be in the opposite direction of the angular velocity vector. Since the car is moving in the North direction, the angular velocity vector would be pointing North. When you slam on the brakes, the car experiences a deceleration, causing the angular velocity to decrease. This means that the angular acceleration vector would be pointing South, in the opposite direction of the angular velocity vector. So, for B, the answer would be South.