# GRE Physics GR 1777 Problem Solution

## 018. Classical Mechanics (Angular Momentum)

### Solution

Angular momentum in a circular motion is

In this problem, two satellites are identical. So the mass of the satellite is equal. The orbital radius of A is the ratio of the angular momentum of A to twice that of B, so

Since satellites have circular motion, the centripetal force is equal to the gravitational force

Then we can wirte angular momentum as

Therefore, the ratio of the angular momentum is

### Answer

(C)

### Reference

https://en.wikipedia.org/wiki/Angular_momentum#Scalar_—_angular_momentum_in_two_dimensions