The forces on projectiles moving through air have been
discussed in many articles33 and books.34 Figure 5 shows the
various forces on the ball. We assume the soccer ball’s trajectory
to be close enough to the surface of the Earth so that
the gravitational force on the ball, mg , is constant. The mass
of the ball is m=0.424 kg.
The air exerts a force on the soccer ball. The contribution
to the air’s force from buoyancy is small 0.07 N and is
ignored. A scale used to determine weight will have that
small force subtracted off anyway. The major contributions