Answer:
Zero
Explanation:
The resultant force acting on the ball would be zero.
Since only two forces were acting on the tennis ball and these forces negate and cancel each other in magnitude, the resultant effect on the tennis ball would be zero.
Assuming that one of the forces is 5N and acting from the positive side and the other force is also 5N but acting from the negative side.
Resultant = -5 + 5 = 0 N
