Physics . average acceleration

Question

clarrise and selia are tennis rivals . during a game , clarrise hit the ball towrds selia ta a speed of 75km/h after 1.5 seconds selia hit the ball back and it travel 82km/h to clarisse . what is the average acceleration of the tennis ball during the 1.5 seconds?

Answer 1

If you copied that down right, this is either a trick question or a stupid teacher.  Quite possibly both, since trick questions usually indicate a stupid teacher.

Not counting gravity or air resistance, the only acceleration took place when Selia hit the ball, which is after the 1.5 seconds are up, so there is no acceleration.

Answer 2

V=u+at   t=1.5s   a=?

82km/hr=82*1000/(60*60)=22.77m/s

75km/hr=75*1000/3600=20.833m/s

22.77=20.83+a*1.5   22.77-20.83=1.5a

1.94/1.5=a   a=1.293m/s^2