# calculus

posted by
**anonymous** on
.

A light is attached to the wall of a building 64 feet above

the ground. A ball is dropped from the same height, but 20

feet away from the side of the building. The height y of the

ball at time t is given by y(t) = 64 − 16t

2

. How fast is the

shadow of the ball moving along the ground after 1 second?