### Whether an object appears to be at rest or in motion depends on your point of view or your “frame of reference.”

A frame of reference uses a coordinate system to establish postion. An observer must use reference points in their surroundings to determine distance, speed, and direction of an observed object.

Galileo, Newton, and Einstein all recognized that the concept of frames of reference was essential when thinking about motion.

How do different frames of reference affect your perception of motion? Use this interactive to find out.

### CONGRATULATIONS!

What you see depends on your point of view, or "frame of reference":

If you see the ball moving east or west, you and the basketball player are in different frames of reference. If you see the ball going straight up and down, you aren't moving relative to each other, you are in the same frame of reference.

Einstein would be proud!

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Side View
Aerial View
You

### Instructions:

You are in a dark room where someone is bouncing a glow-in-the-dark basketball. This is what you see.

You are in a dark room and this is what you see. What combination might cause the basketball to appear this way?

### CORRECT!

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The ball is always bouncing up and down, but you and the basketball player can be standing still, walking west, or walking east, independently of each other.

Your task is to determine the combination of your motion and the motion of the basketball player that might cause the ball to appear this way.