The Physics Behind Ronaldo's Powerful Shot.

Growing up playing soccer, I was always taught that when I go to strike a soccer ball, the follow-through is essential when increasing my shot power. Although the follow-through is a critical factor for shooting a soccer ball, the shorter amount of time the player takes to swing their leg through the air is an even more critical factor when it comes to increasing the power of one's shot. As I grew older and came to understand this concept, and I began to train myself to swing my leg through the air faster to exert more force onto the ball. Although I dislike Ronaldo, it is hard to deny that he has an extremely powerful free-kick. Why is his free kick so powerful? First and foremost, he is able to exert a tremendous force on the ball by increasing the speed of his swing. 

It had been measured that Ronaldo's goal during the 2018 World Cup game Portugal vs. Spain had a speed of 26.8 m/s off of Ronaldo's foot. During this match, the ball was the Testlar 18 World Cup ball, which has a mass 0.436 kg. Therefore, we can calculate the Kinetic energy of the ball upon impact, which was 156.58J. Upon impact, the ball not only has kinetic energy it also has some spring potential energy. However, since the spring potential energy can't be calculated for this problem, we will assume that the total energy of the ball is greater than 156.58 m/s. Using the conservation of energy theory, we can assume that Ronaldo's total kinetic energy prior to coming in contact with the ball was greater than 156.58J. Using this information and neglecting air resistance, we can assume that Ronaldo's swing was greater than the speed of the ball around impact and thus greater than 26.8 m/s. Putting this into context, this means that Ronaldo can swing his leg around 60 mph! 

The faster Ronaldo can swing his leg, the more kinetic energy in his leg and the more kinetic energy can be transferred to the ball, and the faster the ball will move. This makes sense because Force= mass x acceleration, and acceleration is a change in velocity over time. Therefore, the shorter amount of time he can swing his leg, the greater the acceleration will be, and therefore the greater the force exerted on the ball will be. 

The calculations of the speed of the ball, mass of the ball: andhttps://blogs.sw.siemens.com/simcenter/explaining-the-aerodynamics-behind-cristiano-ronaldos-free-kick-with-computer-simulation/