Final answer:
The average acceleration imparted onto the tennis ball by the racquet is -2500 m/s². This is calculated using the change in velocity and the time interval during which the racquet was in contact with the ball.
Step-by-step explanation:
The question asks for the average acceleration imparted onto a tennis ball by a racquet. The ball is initially moving at 20 m/s towards the racquet and is struck so that it moves back in the opposite direction at 30 m/s. The time during which the racquet and ball are in contact is given as 0.02 s.
To find the average acceleration, we must first determine the change in velocity (Δv), which is the final velocity minus the initial velocity. In this case, the ball reverses its direction, so Δv = -30 m/s - (+20 m/s) = -50 m/s (the negative sign indicates a change in direction).
Next, we use the formula for average acceleration (a) which is Δv divided by the time interval (Δt), so a = Δv / Δt. Plugging in the values, we get a = (-50 m/s) / (0.02 s) = -2500 m/s². This negative value indicates that the acceleration is in the opposite direction to the initial velocity of the ball, which is consistent with the way the racquet strikes the ball to reverse its motion.