When a 60 g (=0.06 kg) tennis ball is served by a newly invented machine, it accelerates from zero to 50 m/s. The ball experiences a constant acceleration due to the impact with the racket over a distance of 0.5 m. What is the net force acting on the ball? Use the formula: a= (vf2-vi2)/2d regarding the relation among acceleration a, final velocity vf, initial velocity vi and the traveled distance of an object d.