How can soccer players bend their shots in midair?

We need something else, how about Newton second law? This says that acceleration depends on the net force (F_network) and mass (M) of an object. It is usually written as F_network = m x aBut we can rearrange it as follows: A = F_network/M. Combining this with the force of gravity, we get something interesting:

Courtesy of Rhett Allen

Since gravity and acceleration depend on the mass of the ball, the mass cancels out. We find that any body on Earth has a downward acceleration of 9.8 meters per second per second (m/s²). This means that if you drop a bowling ball and a marble at the same time, they will hit the ground at the same time, even though the force of gravity on the bowling ball is thousands of times higher. Strange, isn’t it?

Anyway, now, in the presence of gravity, if you kicked a ball at an upward angle, its vertical speed would slow down, stop, and reverse, with the speed increasing as it fell. In other words, it starts accelerating in the downward direction as soon as it is kicked, even as it is moving upward.

What about horizontal movement? Ah, since there is no horizontal force after the first kick, the ball continues to move forward at the same speed, just like in space. People tend to think that the ball falls because its forward motion slows down, but in fact the opposite is true. Without air intake you don’t slow down at all. It only stops because the ground gets in the way.

So what we get for trajectory is that familiar inverted parabola, which is often called a ballistic trajectory because it’s the trajectory of any unpowered projectile, such as a cannon ball, a bullet, or a basketball. Any flying object on which gravity is the only force will move in this way.

Football in the air

Fortunately, the Earth has air. But it changes the game radically. Now there He is A constant force acting horizontally, called air resistance, or drag, pushes in the opposite direction of the ball’s movement.

Think of air molecules as a bunch of little ping pong balls. When a soccer ball moves through the air, it collides with groups of these tiny air balls, and each collision exerts a backward momentum; All of this combined, results in a total air resistance force. The larger the object, the more collisions it has to fight through.