Kinetic Friction
Although it is not obvious, when the ball bounces, it slides along the ground for a short distance and actually slows down a little bit due to this brief instant where friction occurred. The force of friction from the court on the ball will always depend on the type of surface the ball is bouncing on. Most community tennis clubs are the same type of court; a medium-paced hard court with average bounce, since different surfaces that cause the ball to bounce lower or higher are more expensive. For this reason, we know that our court falls into the category of ‘typical medium-pace hard court’ in the International Tennis Federation’s Court Pace Rating list (see Data Collection), which gives us the coefficient of friction between the ball and the court. We can then calculate the force of friction on the ball, but first we must find the normal force using our Fnet with multiple forces equation:
Therefore the normal force is 0.54N
We can now find the force of friction using our µ equation:
We can now find the force of friction using our µ equation:
Therefore the force of friction on the ball during the bounce it 0.35N.
Although we cannot see it, we know that friction is occurring at this point because we know that one of the causes of friction is roughness. Tennis courts are intentionally made rougher than normal concrete or asphalt, in order to change the bounce of the ball. Since the court is rough, and the ball is rubbing against it for a brief amount of time, we can tell that friction occurs.
Although we cannot see it, we know that friction is occurring at this point because we know that one of the causes of friction is roughness. Tennis courts are intentionally made rougher than normal concrete or asphalt, in order to change the bounce of the ball. Since the court is rough, and the ball is rubbing against it for a brief amount of time, we can tell that friction occurs.