The tennis ball is smaller in size and uniquely designed for the specifications in it's sport; tennis. The balls are hollow and filled with pressurized gas, accompanied with a two-piece rubber shell, which is covered in felt ,made out of either nylon or wool. I weighed the ball on a digital scale and measured the diameter with a ruler.
Mass: 0.0585kg
Diameter: 6.3cm
Tennis ball
Acceleration & Energy Conservation
The balls light and hollow interior, are key factors in the balls speed and ability to stay in flight longer. The light ball causes it to accelerate faster and maintain its speed once hit by the racket. As the ball bounces we can see energy being transformed into heat and sound, although the total mechanical energy remains the same as no energy can be created or destroyed.
Bounce
A ball must pass ITF (International Tennis Federation) bounce standards of approximately 140cm when dropped onto a regular hard surface court. As a result, manufacturers specify the amount of pressurized air inside the ball, as well as, ensure that rubber shell has enoungh elasticity to bounce. In addition to that, the bounce also heavily relies on the balls compression.
Compression
As the ball hits the tennis racket or the ground it compresses, resulting in the quick and high bounce of the ball. The ball is filled with pressurized gas, aproximately 12 pounds per square inch. When the ball impacts a surface it compresses as shown in the image above, thus pushing that gas up and out of the ball. The rapid movement and reaction of the gas inside the ball, results in its bounce efficiency.
This image demonstrates how the ball compresses upon impact of the racket.
Spin
Upon impact the ball tends to spin off the racket. Depending on how the ball is hit, will the determine if the ball is flat, has topspin, or whether it has underspin. Flat balls tend to be low and slow in the air, and the angle at which it lands is almost the same as after it bounces. A topspin ball is said to be the most effective shot as it travels faster and upon landing, and has a low bounce, thus making it difficult for the opponent to get. A ball with underspin is usually slower, has a much higher projectile, and stays in almost the same position upon landing.
Tennis Racket
A tennis racket, which is constantly held in the players hand is seen as a stiff and rijid piece of epuipment, although its design directly contradicts peoples perception. The racket made of graphite and fibre glass is extremely light weight, and is incredibly diverse in shape, and size, depending on the players preferance. I weighed my racket on a digital scale and meased the length with a tape measurer.
Strung Mass:0.348kg
Length: 68.6cm
Head Width: 27cm
Vibration
Contrary to popular belief of being stiff and rijid, the racket actually vibrates like a wave upon impact. The vibration is used to help catapult the ball off the racket just as easily as it impacted. The handle is the spot with the least amount of vibration on the racket, to protect players from injury. The racket strings have sweet spots that can actually result in a harder, faster and more clean shot. The dead spot or also called a node as shown in the picture, similarly to the handle, has lower vibration, thus having the worst result after impact and directly shaking the handle bar. The sweet spot of the racket is at an anti-node or the yellow Best Bounce spot in the picture. This spot has the maximum vibration in the racket, thus having the energy to push the ball off faster and with a higher force.
This image shows the various impact spots on the racket
Spin
The spin of the ball as mentioned earlier, is initially generated by the motion of the racket and the path of the strings brushing against the ball. By brushing up on the ball, you generate friction, this friction between the ball and the racket creates topspin; the faster you swing in this motion the faster the ball will spin and travel. By slicing or chopping at the ball, you create an under spin. This underspin increases the trajectory and projectile height of the ball which causes it to stay where it lands. The flat ball is created when the racket impacts the ball with an open face meaning the racket head is open and straight. The straight motion of the ball stops the spin from generating and the ball tends to travel slower, or is less effective.
Depending on the motion of the racket, the friction between the two objects, will generate different spins.
Strings
The strings are especially important in the whole composition of the racket, as it is directly impacting, and brushing against the ball, thus determining the amount of friction created. The strings are predominantly made of a material called catgut, which allows the strings to slide on one and other. This material is bendable and thus has a certain level of elastic energy that causes the ball to bounce right off the racket. Once the string slides, it flips right back in place upon impact of the ball, thus the ball flies off. Like inertia the string want to stay stationary thus reverting back to their original positiondirectly after impact on the ball.
This video demonstrates how physics plays a role in tennis equipment.