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# Physics/Golf Ball at terminal velocity hitting pedestrian.

Question
Hi there Steve,
I would like to start off by saying i'm not very experienced in physics by any means, so feel free to simplify things at any point.

This is very much like the classic myth of a coin killing someone if dropped from the Empire State Building. We know that a coin that has reached terminal velocity won't kill someone let alone injure them.

Recently we watched a video of someone, as a prank, sending golf balls into the air with balloons.
It occured to us that those balloons would pop eventually, releasing a golf ball with what we assume to be plenty of room to reach terminal velocity before impacting the ground.

My question is, would that golf ball actually stand a chance of killing someone if it were to hit them? If not killing them, to what extent of damage would be done?

That's a pretty mean prank, really, because it could certainly damage things like cars.  Hailstones do that, and they're falling spheres.  Basically the mass of a regulation golf ball is at least 45.93g and the minimum diameter of 42.67mm.  That gives it (it's a little more than this with the dimples) a terminal velocity of 16.7 m/s.  That really not all that much faster than a human being can run (they can run a little over 10 m/s), but because of its small size that's not very much energy.  Makes the energy density something like the energy density of a runner's hands or feet.  It would hurt if it hit you, possible dent a hard surface, but it's not going to damage the roof of a house or a road surface.

Physics

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#### Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.