Physics kinetic energy question!?

Question

Hi can somebody answer this questions please. I don't just want the answer, i would also like to see the working out please.

If a football is kicked upwards, such that it has an initial velocity of 15 m/s, then calculate how high it would rise (delta h) into the air. (hint: first calculate its kinetic energy, and thus the maximum gain in potential energy, rearrage a formula to find h)

Many thanks,

best answer gets 10 points.

Update:

Thanks george for the answer, but i don't get it. Is the question wrong, as we need the mass? i don't know how to solve it without the mass.

Answer 1

Favorite Answer

As you do not know the mass of the football it's KE = (mass) * v^2 = Nv^2

where N is its mass in Newtons and v = the initial velocity

As the ball reaches its maximum height the KE = zero Nu^2 = 0

where u is its final velocity = 0

from the formula v^2 = u^2 + 2ah where

a = acceleration due to gravity

h = the height

then h = (v^2 - u^2) / a where u = zero

The mass of the ball does not enter into the formula