# Physics

posted by
**Jane**
.

a) Newton's law of motion states that the acceleration acting on a falling body

(assuming no other forces) is

x" = -g, where x(t) is the height of the object

above the ground, t is time, and g is the gravitational constant. Find a general

expression to describe the height of the object above the ground with respect

to time, t; i.e. find x(t).

(b) Suppose the object is dropped from a height of 100 units (so x'(0) = 0 and

x(0) = 100), how long will it take to hit the ground?