We have already seen that all objects fall with the same acceleration, 9.8 m/s/s (which we approximate as nearly 10 m/s/s).

We call this free fall.

When such objects fall, the only force acting on them is their weight, the force of gravity.

The only force on a body in freefall is the force of gravity. We call this its weight.

Since it accelerates at 9.8 m/s/s,

that weight must be

w = (mass)x(9.8 m/s/s),

w = mg

The weight of an object is the force of gravity on that object.

Weight, since it is a force, will be measured in units of newtons (N).

Mass will be measured in kilograms (kg).

F = m a

Third Law
Return to ToC, Ch4, Newton's Laws of Motion

(c) 2002, Doug Davis; all rights reserved