Impulse, Acceleration and Momentum
Impulse and Momentum are two key biomechanical factors that are used in the tennis serve. Impulse is “the product force, multiplied by the time that a force acts.” (McGinnis, 2005). Momentum is the product of mass and velocity (Blazevich, 2012). So in order to increase an object’s momentum, we need to increase the impulse.
In order to increase the momentum of a tennis ball in a serve (increasing it’s speed and velocity), the impulse force of the racquet needs to be increased. Newton’s second law states that: “the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object: Force=mass X acceleration (F=ma)” (Blazevich, 2012). Hence, the easiest way to increase the momentum of the tennis ball is to increase the acceleration of the racquet before it makes contact with the ball. This also means increasing the speed of the torso and arms. This allows faster movement of the racquet (see kinetic chain). The greater the acceleration of the racquet during the wind-up stage, the greater the force in which is applied when connecting with the ball. This will in turn increase the momentum of the tennis ball and increase the speed of the ball.
Having a heavier racquet will also increase the impulse (F=ma). A racquet with a greater mass, generally means more power for the player when they execute strokes(Rutherford, 1999)(Babolat, 2013). Table 1 shows the difference between two Babolat racquets in terms of mass and their favour in relation to power and control.
In order to increase the momentum of a tennis ball in a serve (increasing it’s speed and velocity), the impulse force of the racquet needs to be increased. Newton’s second law states that: “the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object: Force=mass X acceleration (F=ma)” (Blazevich, 2012). Hence, the easiest way to increase the momentum of the tennis ball is to increase the acceleration of the racquet before it makes contact with the ball. This also means increasing the speed of the torso and arms. This allows faster movement of the racquet (see kinetic chain). The greater the acceleration of the racquet during the wind-up stage, the greater the force in which is applied when connecting with the ball. This will in turn increase the momentum of the tennis ball and increase the speed of the ball.
Having a heavier racquet will also increase the impulse (F=ma). A racquet with a greater mass, generally means more power for the player when they execute strokes(Rutherford, 1999)(Babolat, 2013). Table 1 shows the difference between two Babolat racquets in terms of mass and their favour in relation to power and control.
Table 1.1: Tennis Racquet Comparison: Mass v Power
Source: Babolat, 2013.
In the table above there are two different types of racquets. The racquet on the top is the Pure Drive (blue racquet) and on the bottom is the Pure Storm (Red Racquet) (this is also the racquet i use in the videos on this blog). The Pure Drive is heavier in mass which allows the racquet to generate more power than the Pure Storm. The Pure Drive can be more powerful, however, more mass requires a greater force to create high acceleration of the racquet. This can cause a player to fatigue earlier and cause strain on the body due to the repetitive nature of the game (Rutherford, 1999). It may also not be practical for other areas of the game (such as ground strokes) if it is difficult to move. Hence, it is important to select a racquet that is optimal for all areas of the game and accommodates the strengths and weaknesses of the player.