if a person jumps off a building and hits after 5 sec and the building is 55 ft tall how fast are they going?

Question

maximum velousity

Answer 1

Average velocity would be 11 feet per second. Instantaneous velocity would depend on which time interval you were looking at. As the person falls, the velocity increases. Acceleration is 9.81 meters/second squared.

Answer 2

That person does NOT hit the ground after 5s because acceleration due to the earth is always constant and both velocity and time are specific at a certian height. In this case, the person will hit the ground at t = sqrt(2y / g) = sqrt(2(55)/32) = 1.854s. We can not just say the person hit the ground at 5s. The time in this problem is an invalid information.

To find the speed, use this formula:
Vf^2 = 2ad + Vi
Vf^2 = 2(-32)(0 - 55) + 0^2
Vf^2 = 3520
Vf = -59.33 ft/s

Answer 3

Ah, I see the other responders were making assumptions that weren't specified in the question (such as, that the building is on the earth). I will take the question at face value.

Since they covered 55 ft. in 5 sec, the average speed is 11 ft. per second.

If they're in a uniform gravitational field (i.e. accelerating uniformly), then their change in velocity is twice their average velocity; or 22 fps.

So, if the started a zero fps when the jumped off, they're going at 22 fps when they hit the ground.