Science Buddies: "Ask an Expert"

hi! i am doing science fair project about the effect of wrists(hand is included) angle on accuracy of directions and height that balls go in volleyball. but i don't know how to conduct my experiment.
My science teacher said i can't use real people's wrists to do it because i can't conduct same angles and forces each time!
what should i do?
this is urgency. he wants me to do it for this weekend. thank you for reading and please reply this
have a great day!

Dear Leehusy,

As a former volleyball player, this project is very interesting to me. However, as your teacher pointed out, you may have difficulties experimenting with the subject. You need a machine that could throw a ball with the same strength and direction consistantly as well as a wrist-like surface to deflect the balls. I suggest speaking to a sports trainer or expert about the kind of devices they use for training. Perhaps you could use a tennis ball machine instead? Then once you got the ball hitting where you want, you could change the angle of the wrist. It makes sense that there would be a good trend that you could discover, so I hope this helps!