Question

Two particles move in opposite directions to what along a straight line (see figure). The particle of mass m is moving to the right with velocity v while the particle of mass 3m moves to the left with speed v. What is the total angular momentum of the system about a) point A, b) point O, and c) point B?

A) A) 2mvR
B) -2mvR
C) -4mvR
D) 4mvR

Answer 1

The total angular momentum of the system about point A is -2mvR, about point O is zero, and about point B is 2mvR.

Step-by-step explanation:

To calculate the total angular momentum of the system, we need to consider the individual angular momenta of the particles and add them together.

a) The total angular momentum about point A is the sum of the angular momenta of the two particles. Since the particle with mass m is moving to the right and the particle with mass 3m is moving to the left, their angular momenta have opposite signs. Therefore, the total angular momentum about point A is -2mvR.

b) The total angular momentum about point O can be calculated by considering the distance of each particle from O. Since both particles have the same speed v, their angular momenta are the same in magnitude. Therefore, the total angular momentum about point O is zero.

c) The total angular momentum about point B can be calculated similar to point A, by considering the opposite signs of angular momenta. Thus, the total angular momentum about point B is 2mvR.