How long will it take for an object dropped from a height of 100 meters to hit the ground?

With air resistance is it 4.7 and without is it 4.5? (seconds)How long will it take for an object dropped from a height of 100 meters to hit the ground?
here's the answer without air resistance:





s = s0 + v0(t) + 1/2(a)(t^2)





s = -100 m


s0 = 0 m


v0 = 0 m/s


a = -9.8 m/s^2





-100 = 0 + 0 + 1/2(-9.8)(t^2)





-100 = -4.9(t^2)





t = SQRT(-100/-4.9) = 4.5 seconds





You would need more information to take air resistance into account (i.e the objects drag coefficient and cross sectional area). But the time of the fall would be more than 4.5 seconds...How long will it take for an object dropped from a height of 100 meters to hit the ground?
Air resistance is highly variable depending on the object (think of a feather and a pebble with the same weight) so an answer of 4.7 seconds doesn't mean anything.





S=1/2gt^2





t^2 = 2s/g = 200/9.8 = 20





t = 4.5 seconds