<em>You wrote the whole answer right there !</em>
The GPE it has when it's dropped IS exactly the KE it has when it hits the ground. So you just write (KE at the bottom) = (GPE at the top).
Like this: M · g · h = (1/2) · m · v²
Divide each side by M :
g · h = (1/2) · v²
Multiply each side by 2 :
2 · g · h = v²
Take the square root of each side:
<em>Speed = √(2 · g · h)</em>
What things do you know in this equation ?
-- 'g' is 9.81 m/s².
-- 'h' is the height it dropped from.
-- You know what '2' is.
-- You know how to do a square root on your calculator.
-- Pluggum all in, and you have the speed when it hits the ground.
Notice that the mass of the object went away ! It doesn't matter whether it's a coin or a car. It only depends on gravity and the height it's dropped from.
