# How would a newtons cradle act in zero gravity?

I imagine that the first ball would strike the rest as normal, but what would the last ball do, without gravity to swing it back?

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You might have to throw the first ball rather than just letting go. – Henry Sep 11 '11 at 22:51

## 2 Answers

My assumption is that it would react the exact same way as it would on Earth (in a vacuum) or any similar instance where the pull of gravity is relatively uniform (also in a vacuum). By uniform, I mean a gravitational pull whose net force is in the direction of an arrow perpendicular to the balls.

If it were suspended in space, the nearest/strongest gravitational pull to the last ball would probably be the other balls (unless the strings and poles on which the balls are suspended are much denser/massive), in which case it would end up all jumbled.

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in order to avoid jumbling due to zero gravity, use rigid rods with bearings to hold the balls. – Waqar Ahmad Sep 28 '13 at 5:13

It would rotate around through most of a 360${}^{\circ}$ arc, until it collided with the second to last ball on its way back around. Then the whole thing would end up mucked up.

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You need to insure that the frame is heavy with respect to the balls to insure that this happens neatly, of course. – dmckee Sep 11 '11 at 23:54
Would a rotating space station fix this? Could you design a zero G Newtons cradle? – Pureferret Jan 3 '12 at 18:38