How long does it take for a person of average weight to fall 30m?

Answer 1

First of all ... Your question clearly displays a popular misconception that Galileo proved false 500 years ago. Gravity does not pull heavier things down faster. Technically, the weight doesn't matter.

If you can eliminate the effects of air resistance, then anything you drop from the same height hits the ground at the same time, whether you drop a feather, a Baseball, or a brick.

The acceleration of gravity near the earth's surface is 9.78 meters per second2. The distance an object falls in 'T' seconds is 1/2 G T2 = 4.89 T2.

You want 30 meters ? OK.

30 = 4.89 T2

T2 = 30/4.89

T = sqrt(30/4.89) = 2.477 seconds, whether it's a feather, a baseball, or a brick. As long as you drop it rather than throw it down, and as long as air has no effect.

Of course we know that air does have an effect. That's how one skydiver can catch up (or catch down) with another skydiver who jumped first.

From your question, we have no information on whether your average-weight guy is streamlining himself or spreading himself out. So the best we can do for you is to ignore air and give you the gravity-only answer above.