A tennis ball hit by a racquet also experiences a 0.56 newton force of gravity, which is excluded from the racquet force calculation because it:

1. The calculation asks specifically for the average force exerted by the racquet. 2. Several forces act on the ball during the impact. 3. The quantity computed was the average force exerted by the racquet on the tennis ball during its brief impact. 4. Note that the ball also experienced the 0.56 newton force of gravity, but that force was not due to the racquet. 5. Attributing it to the racquet would overstate what the player actually did. _Source: OpenStax College Physics for AP(R) Courses 2e (CC BY 4.0), Ch 8 'Linear Momentum and Collisions', sections 8.1-8.7_