Can you run faster on the moon?

06 September 2009

Question

My son Joshua and I were wondering if Usain Bolt was to go sprinting on the moon, he’s the guy who’s this amazing athlete from the Caribbean who seems to be able to run faster than anyone else ever thought was possible. If he was to go sprinting on the moon but without being hindered by extra weight like space suits and equipment and so on, would he run faster or slower than on earth? I believe gravity is a bit weaker, but I’m not sure if that would be a benefit for locomotion or not?

Answer

Dave - On the moon, the gravity is about a sixth of the earth so you can jump much, much higher. Whether this helps you with running, it depends on what kind of running you're doing, I think. If you're trying to sprint, if the sixth amount of gravity then you're going to have a sixth of the amount of friction between your feet and the floor because friction basically goes at how hard you're pushing against the floor, and this means - but your mass is still the same, so you still need the same force to accelerate. So, he'll be able to accelerate about a sixth of the rate as he could do normally. So, in a 100-meter sprint, he's almost certainly going to be a lot slower. But if you're running a very long way, you could probably get an advantage because you can take huge strides. So, you can sort of - you could take a huge stride and then not do anything for a three or four seconds while you fly through the air and then you can land and do a little bit of exercise and fly through the air for a bit. So, you get some time to recover in between so I think you could probably run long distances faster, but short distance is not maybe as quickly.Diana - So, it'd be like the laziest race ever then, wouldn't it basically?Dave - Oh, it depends how fast you're going but, yeah.

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