The Physics of Soccer

Body Mechanics of Kicking

Fastest shot ever recorded https://www.youtube.com/watch?v=MBMmJ438R6sForce=Mass*AccelerationForce=Mass*(Velocity/time)F= .43kg*((52.5m/s)/.338 sec)F= 66.79 NComparable to getting a punch in the face from an eight year old!!!

The Force of a Soccer BallForce of an average high school player’s shot:0.43kg*15.82/1.04=6.54 N

The Magnus EffectAs the ball undergoes top-spin (shown as clockwise rotation in the figure), it causes the velocity of the air around the top half of the ball to become less than the air velocity around the bottom half of the ball. This is because the tangential velocity of the ball in the top half acts in the opposite direction to the airflow, and the tangential velocity of the ball in the bottom half acts in the same direction as the airflow. In the figure shown, the airflow is in the leftward direction, relative to the ball.

Since the (resultant) air speed around the top half of the ball is less than the air speed around the bottom half of the ball, the pressure is greater on the top of the ball. This causes a net downward force (F) to act on the ball. This is due to Bernoulli's principle which states that when air velocity decreases, air pressure increases (and vice-versa).

Therefore, when a soccer player kicks the ball right of center the ball spins counter-clockwise and the Magnus force acts left, causing the ball to curve left. When the ball is kicked left of center the ball spins clockwise and the Magnus force acts right, causing the ball to curve right. This can result in a ball deviating as much as several feet from the original trajectory by the time it reaches the net. This is no doubt a useful strategy when attempting to make a goal, since it makes the path of the ball less predictable to the goalie as he's preparing to block the shot.

the magnus effect

How Soccer Relates to each of Newton’s LawsNewton’s First Law

A soccer ball will stay at rest until a soccer player applies force onto the ball, putting it into motion, the ball would stay in motion if it wasnt for the earth’s gravitational pull.

Newton’s second law:The acceleration of the ball is equal to the force applied divided by the mass of the ball. The heavier the ball, the more mass needed to accelerated. Aka a stronger leg.

Newton’s third LawEvery time you kick a soccer ball, the same force is applied to your leg by the soccer ball,there is less movement simply because your leg has more mass compare

Angular VelocityRoberto Carlos’ famous curvehttps://www.youtube.com/watch?v=3ECoR__tJNQ

Angular VelocityAngular velocity= 10 rev/second or approximately 31.4 rad/second

Resulting in over 2.6 meters of horizontal distance traveled or 8.5 feet over a distance of 10m.

Average Force to Stop a shotWe will assume for this scenario that the collision between the goalie’s hand and the ball is perfectly elastic. Therefore we know that the force needed to send the ball back on the same path it came from must be slightly more than the force of the ball.