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15

2kW is not that much on Earth You've mentioned radiation and convection in your answer (you forgot conduction). Turns out the properties of Earth's atmosphere make conduction and convection way better than radiation for moving heat around. For an illustration, consider the size of a portable, 2kW, oil-filled radiator: this one lists the size as ...


14

It still has the resistance of terrain against wheels (well, weaker than comparable terrain on Earth due to lower gravity - but then the terrain is pretty awful for driving), the same friction of bearings and so on - a car driven through loose sand on Earth will stop really fast due to the sand resistance, and not due to air. Now if instead of a lunar rover, ...


5

Cars and also lunar rovers are slowed down by wheel bearing fricition and rolling resistance of the wheels on the ground. The rolling resistance of the wheels is reduced by a perfectly flat terrain with no dust but it will never be zero.


2

It's the tiny payload that matters--the rocket is lighter than normal so the same thrust causes it to move faster. This is because it's heading to Mars instead of to orbit, they are trading payload capacity for the speed needed to get there. It's not going to make a big effect in the liftoff speed, though, the weight of the payload is quite small compared ...


1

There are a lot of ions in space already, adding a few from the thruster is not really that big of a deal. They are moving so fast that it won't really make a huge difference being neutral or not, they are going away from the spacecraft, and at the point where electrons are typically injected they are far enough away that it doesn't matter much. All that ...


1

The other answers are good, but let me offer a more general answer. If the train or car did go on forever (effectively orbiting the moon, but on land), then you would have discovered a perpetual motion machine. See here for why that's impossible.


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