Hypothesis
The racquet with the lower tension level will make the ball travel faster.
Overview
Tennis racquet and ball speed
The speed that a tennis ball travels at after being hit by the racquet is determined by the power/strength of the player and the speed with which the racquet is swung. As different parts of the racquet will be traveling at different speeds during the swing, the location at which the ball hits the racquet also affects the resultant ball speed.
The power of the racquet is determined by its weight, the stiffness of its frame and the tension of the strings. The weight of the racquet is important in determining the potential power: the heavier the racquet, the higher its potential power. It is also most powerful at the balance point of the racquet, also called the “sweet spot” and normally located about 75mm above the neck of the racquet. Hitting the ball at other spots will cause the racquet to spin or recoil upon impact.
A racquet frame that lacks stiffness can cause the racquet to bend or twist upon contact with the ball. This will result in loss of power due to the bending action - if the racquet does not spring back in time, the ball would not have launched with maximum speed and power.
If the string tension of the racquet is too high, it will cause the shape of the ball to deform upon impact. In the centre of the string bed, the strings are longer and able to provide more cushioning, resulting in less ball deformation and less energy loss. If the tension of the strings is too high, or the ball is hit off-centre (where the strings are shorter), ball deformation will cause the tennis ball to lose up to half of its energy.
Scientific Terms
Stiffness, tension, potential power
Conclusion
The hypothesis that the racquet with the lower string tension will make the ball travel faster, is proven to be true.
The speed of the ball is determined by the combination of racquet speed and power. When the ball is hit near the neck of the racquet, more power is gained but te speed is lost. Hitting the ball near the tip of the racquet will provide greater speed but it will lack in power. It is therefore up to the player to find the best spot at which to hit the ball, such that it complements the player's strength, speed and skill.
Also consider
This science fair project can also be conducted using racquets of different weights.
Perhaps you could also measure the distance traveled by the ball?
References
Why is maximum power in the throat and the maximum shot speed toward the tip? - http://twu.tennis-warehouse.com/learning_center/PPandspeed.php
Power: Does the racquet matter? - http://twu.tennis-warehouse.com/learning_center/racquetcontribution.php
Related videos
Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
