Transcript Science of Soccer - North Allegheny School District

The Physics of Soccer
Body Mechanics of Kicking
Fastest shot ever recorded
https://www.youtube.com/watch?v=MBMmJ4
38R6s
Force=Mass*Acceleration
Force=Mass*(Velocity/time)
F= .43kg*((52.5m/s)/.338 sec)
F= 66.79 N
Comparable to getting a punch in the face from
an eight year old!!!
The Force of a Soccer Ball
Force of an average high school player’s shot:
0.43kg*15.82/1.04=6.54 N
The Magnus Effect
As 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
Laws
Newton’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 Law
Every 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 Velocity
Roberto Carlos’ famous curve
https://www.youtube.com/watch?v=3ECoR__
tJNQ
Angular Velocity
Angular 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 shot
We 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.