Final answer:
The maximum width of a tennis racket's hitting surface according to ITF regulations is 11.5 inches. Using physics and projectile motion, one can determine the angle and trajectory needed for a tennis ball served at 170 km/h to clear the net and land in the service box.
Step-by-step explanation:
The regulation size of a Tennis racket's hitting surface cannot be larger than 11.5 inches in width. This falls within the regulations set by the International Tennis Federation (ITF) for the acceptable dimensions of a tennis racket. As for the tennis scenario presented, the problem involves physics concepts such as projectile motion, which can be used to calculate the angle at which the tennis ball must be served to just cross the net and whether it will land within the service box. Serving at a speed of 170 km/h and at a certain angle below the horizontal, the ball needs to be aimed carefully to ensure it crosses the net at 0.91 m high and lands within the service box, which is 6.40 m from the net. Calculating this angle would require a knowledge of kinematic equations and a good understanding of the principles of projectile motion.