
40 Chapter 1 Law of Action and Reaction
Yes, that’s exactly it. In short, F
hand
and F
gravity
are vectors of the same magnitude in
opposite directions, resulting in zero when added:
the force exerted by the hand on the ball + force of gravity on the ball = zero
Now, let’s look at forces in terms of magnitude only, not as vectors with direction.
As explained on page 37, the magnitude of a force is expressed as |F
hand
| or |F
gravity
|,
using absolute value symbols. Developing these expressions further, you get equations
like |F
hand
| = F
hand
and |F
gravity
| = F
gravity
. Now you know the two forces have an equivalent
magnitude, which can be ...