You drop a pencil out of window that is 20ft above the ground. Use the formula V^2=64s, where V is speed and s is the distance fallen, to calculate the speed the pencil is traveling when it hits the ground.

First you substitute in the values so you have

V^2 = (64) 20

then you just simplify it

V^2=1280

V=the square root of 1280

V = about 35.7770876

or

V=the square root of 256 times the square root of 5

V=16 times the square root of 5

also V would typically be called velocity. it's very similar to speed but it is just easier to remember because it starts with a V