Subject: How can I measure the vibrations of a ball hitting a tennis racquet?

I'm working on my science fair project.  I will put the tennis racquet 
in a vise grip and tie a cord to a tennis ball.  The ball will be 
released from the same point each trial.  I need to know the best way 
to measure the vibrations produced by the ball on the strings of the 
tennis racquet.

Re: How can I measure the vibrations of a ball hitting a tennis racquet?