posted by jake .
a 50 kg crate is lifted to a height of 10 meters.
a. how much potential energy does the crate have after being lifted?
b. if it took 5 seconds to lift the crate, using a machine what was the power rating of the machine?
a) Work = Force x Distance
The Force in this case is Mass*(acceleration of gravity), so
Work = 50 kg*9.8 m/s^2*10 m = __ Newtons
b) Power = Work/Time
one half second after starting from rest, a free falling oblect will have a speed of about what?