Question

If you let yourself fall from the top of a building that is 22m high, how much time will it take to reach the floor AND what will be your final speed.

How do i approach this problem?

Answer 1

By using Conservation of Energy. All of the gravitational potential energy, PE, of being at 22m height will be converted into kinetic energy, KE.

Hence, write down expressions for PE and KE and set them equal to see what the speed will be when you hit the ground. Your answer should have a square root in it somewhere.

Answer 2

Additionally, to find the time, we can use the following equation of motion for constant acceleration: \[d = {1 \over 2} at^2\]

Answer 3

eashmore is somehow correct..
your question is all about free fall bodies, thus its initial speed/velocity(Vi) is ZERO(0).
Given: distance(d)=22m,
Vi=0,
time(t)=?,
final speed
(Vf)=?
acceleration due to gravity (g)= \[9.8 m/s^2\]

solution: \[d= V{i}t +1/2gt ^{2}\], since Vi=0, thus the equation will be this:
\[d=1/2gt ^{2}\]--same as eashmore
but then you must still derive this to get the time: so,
\[t=\sqrt{2d/g}\]
substitute your given data...time must be \[t=2.1m/s ^{2}\]

for the Vf: the formula can be this: \[Vf= Vi + at\], again Vi=0 so, substitute:
\[Vf=at\]... the answer is: \[Vf= 20.58 m/s\] or \[21m/s\]...

just try if that's correct! hope it helps!