# Space 10.17

1. Jun 2, 2006

### jmccray

Suppose you were kidnapped and held prisoner by space invaders in a completely isolated room, with nothing but a watch and a pair of shoes (including shoelaces of known length). Explain how you might determine whether this room is on earth or on the moon.

Last edited: Jun 2, 2006
2. Jun 2, 2006

### Danger

Personally, I'd just determine whether or not I seemed to be at my normal weight. Is this homework?

3. Jun 2, 2006

### jmccray

just something a teacher asked us to think about and discuss tomorrow.

4. Jun 2, 2006

### Danger

There are lots of ways that you could do it, such as dropping the shoe and timing its fall with the watch (if it's accurate enough). Gravitational acceleration will obviously be different. I get the impression, though, from the specific mention of shoelaces, that your teacher is looking for a pendulum whose oscillations you can time.

5. Jun 2, 2006

### AlphaNumeric

Either measure a set height above the ground, drop your shoes and time the time taken to hit the ground (then use equations of motion to find gravity) or do as Danger suggests and make a pendulum and use oscillation equations to find gravity.