How to Calculate Circular Motion

Objects traveling around a circle have angular momentum.

Velocity is generally a measure of how fast an object is moving in a straight line. Momentum is how much force that object is exerting given its velocity and its mass. The more mass an object has, the more momentum, which is to say that the bigger something is, the harder it is to stop. Momentum is literally the tendency to keep moving. Angular momentum is just the same, except that instead of moving in a straight line, the object is moving in a circle.

Instructions

1. Determine the radius of the circle the object is traveling around. For example, a person might be hanging off the side of a merry-go-round with a 10-foot radius.

2. Determine the mass of the object. In our example, the person's mass might be 100 kilograms.

3. Determine the linear velocity of the object. If the object makes a complete revolution once per minute, for example, then it's going 10^2 x pi or about 314 feet per minute.

4. Multiply the radius by the mass by the linear velocity to find the angular momentum. 10 feet x 100kg x 314 feet per minute is 314,000 kilogram feet squared per minute.

Tips & Warnings

• If you just want to find the angular velocity of an object, you only need to complete Step 3, which tells how fast the object is moving around the outside of the circle.

References

• Angular Momentum