Will slinky length be different on the moon?

Question

If we hold one end of a slinky and leave other end free, the earth's gravity applies force on the slinky and it expands. If we do the same on the moon with the same slinky, will the acquired height of the slinky be different?

score 35 · Accepted Answer · answered Nov 17 '20 at 13:44

Simple answer yes,

Think about taking two extreme cases :

How much does a slinky extend in a gravity-free space? None at all

How much would it extend if it was on perhaps Jupiter or even a black hole ?It should extend by a large amount.

Gravity does play a role.

score 8 · Answer 2 · answered Nov 18 '20 at 12:41

For a typical slinky (wiki) and comparing the gravity of earth and moon, this will be the case as outlined by the other answers.

However, for a general spring (wiki) or weaker gravity fields, the spring may be in a state where it is fully contracted and the weight of its own mass is insufficient to stretch it at all. In that regime, gravity does not play a role.

score 6 · Answer 3 · edited Nov 18 '20 at 11:10

6

If a slinky is hanging vertically in a gravitational field, the amount of stretch in any short section depends on the weight of the coil hanging below that section. Less gravity will produce less stretch.

edited Nov 18 '20 at 11:10

ohneVal

4,528

answered Nov 17 '20 at 14:40

R.W. Bird

12,280

score 2 · Answer 4 · answered Nov 17 '20 at 14:52

2

Does the solution to:

$$ \frac{dU}{dz} = \frac d {dz}[U_{spring}(z)+U_{gravity}(z)] =\frac d {dz}[\frac 1 2 k z^2 - \frac 1 2 mgz]=0$$

depend on $g$?

answered Nov 17 '20 at 14:52

JEB

42,131

Will slinky length be different on the moon?

4 Answers4