- #1

leibniz33

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A small, low-mass body is moving at a constant velocity of 1000m/s through a vaccuum, so it has no acceleration or deceleration i.e. a=0. Now let's say you are an astronaut and you are floating directly in the path of this oncoming body. You are completely stationary i.e. you have zero velocity. The small body collides with you. According to Newton's 2nd law, Force = Mass x Acceleration, so if you want to calculate the force F carried by the small body that hits you, you should be able to use this formula. However, if a=0, then F = m(0), therefore F=0. How can a body moving at 1000m/s hit you and impact no force on you?

Bear in mind that this is intended purely as a hypothetical. Of course in actual space, the gravity of nearby large bodies like planets/moons/stars would give a certain acceleration to the small body. However, even if a very small moon was nearby and it gave the small body an acceleration of 0.01m/s^2, this would still result in a very small F value, much less than would be expected of something traveling at 1000m/s. I'm sure there is a very simple explanation for this, but i haven't been able to find one yet.

Cheers.