Most of the deflection of the ball occurs in the second half on the ball's flight, making it even more difficult to detect. Ask the students to draw force diagrams of the different spin situations, top and back, based on the motion of the ball in the wind tunnel. Ask them to predict the paths of the ball compared to a non-spinning ball. Ask them to predict the effects, draw force diagrams and describe the paths of balls thrown with side spin. The force of gravity and forces arising from air resistance have the most measurable effects.
Gravity forces the ball to accelerate downward dramatically during the flight.
A non-spinning ball undergoes a significant drag force while in flight, reducing the ball speed by as much as 10 mph. Because gravity has such a dramatic effect on a thrown ball, it is difficult to see the more subtle effects of air resistance. The largest Magnus force on a very well thrown curveball is only one third the effect of gravity, and it acts in approximately the same direction, making the effect very difficult to see. In this activity, student will model the trajectory of a ball under the influence of only a small force such as the Magnus force. By controlling the greater effect of gravity, they can understand how these smaller forces alter the otherwise predictable path of a pitched ball.