# Mini-Quiz: Center of Mass and Radial Gravitational Motion

by Ron Kurtus (revised 14 May 2011)

Take this Mini-Quiz to check your understanding of the lesson material.

1. What does mvRm = −MvRM indicate?

It means that vRM is less than zero

The equation is incomplete

The negative sign indicates that vRM is in the opposite direction of vRm

2. What can happen when the objects are moving away from each other with respect to the CM?

They start to go into orbit around each other

They may reach a maximum displacement and reverse directions

One object will stop while the other continues on

3. What happens to the CM if it appears to you that the objects are moving in the same direction?

The CM also moves in that direction to an outside observer

The CM stays where it was originally

The CM moves in an opposite direction of the objects

If you got all three correct, you are on your way to becoming a Champion in Physics. If you had problems, you had better look over the material again.

Consider all the possibilities

## Resources and references

Ron Kurtus' Credentials

### Websites

Center of Mass Calculator - Univ. of Tennessee - Knoxville (Java applet)

Center of Mass - Wikipedia

Gravitation Resources

### Books

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