Shooting a soccer ball is an effective illustration of the laws of physics. A simple example is kicking the ball lightly. You don’t transfer much energy, so the ball doesn’t travel far. Changing the point of contact also affects the ball’s flight path. For example, if you kick the ball below the center, it will travel upward at a sharp angle. When you’re shooting at the goal from a close distance, this might send the ball high over the goalposts.
Energy
Energy is always conserved, though it may be transformed. In the context of shooting a soccer ball, your body transforms the energy you receive from the nutrients in your diet into physical movement. You transfer that energy to the ball by contracting your muscles so your foot contacts the ball. Once the ball hits the net inside the goal -- or if you’re less lucky, the goalkeeper’s hands -- the ball transfers its energy to whatever it contacts. For example, the ball’s momentum might cause ripples in the net.
Resistance
Objects in motion tend to stay in motion. Imagine that you kick a ball while in the vacuum of outer space, far from any objects that could exert a gravitational force. The ball will travel forever in whatever direction you kicked it. Only if another object exerts a force will the ball stop. When you kick a ball on Earth, two major forces cause the ball to deviate from the straight-line path it would otherwise take. First, gravity pulls the ball down toward the center of the planet. Second, the air the ball travels through resists the ball. This resistive force is called friction.
Effect
Soccer players who bend the ball exploit a freakish effect of friction. A bending ball travels straight at first but quickly begins to curve to the side. To achieve this effect, kick the ball so it spins sharply to one direction. In other words, contact the ball slightly to the right or left of center, and use a swiping motion to impart spin. The friction the air applies will differ on either side of the ball because the air passing by on one side will be heading in the direction of the spin. On the other side, the direction the air travels is opposite to the spin. The different air pressures on either side of the ball result in a sideways force that causes the ball to follow a curved path.
Considerations
Experiment with different kicks to determine how to shoot the soccer ball effectively. Typically, kicking with the top of your shoe near the laces is the most efficient way to transfer energy, so it will create the most powerful shot. Try contacting the ball at different places to see what effects you can create. For example, if you hit the ball slightly above center, it will be a low and speedy shot.
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