# 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?

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, 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-metre 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.

## Related Content

### astronauts throwing things in slow mo

It's odd that NASA would show astronauts throwing things around in slow motion, and driving the lunar rover, again obviously everything moving in slow motion. When the astronauts were throwing stuff it was very obvious things were flying in slow motion.

However: When objects move through an environment with very little air..they can move faster because there is less air resistance. Everyone already knows this is true because we have all seen objects dropped in vacuum chambers. But, when objects move through very thick air, they are slowed down more by the air resistance to the point of where they are moving through water.

So...we know that objects in a vacuum do not move slower than objects thrown around here on Earth. If anything, throwing an object in a vacuum might make you able to throw them faster and further because there is very little air resistance.
On the other end of the scale, we know that objects moving through water for example, where there is a lot of resistance to movement..things really look like they are moving in slow motion, and its very hard to throw things fast and far while your under water.

KNOWING all of this: WHY is there film footage of slow moving objects in a vacuum, released by NASA? Don't they know it's bad physics?