Hello! I am doing a sample exam that was given out last year so I can prepare for this years coming exam, which means I also have the answer key. So, I know the answer to the question but I am no sure how to get it. Please help, thanks. A tennis ball and a ball made of putty of the same mass are thrown against a brick wall. Which of the following statements is true? a) the change in momentum of the tennis ball is greater b) the change in momentum of the putty ball is greater c) the change in momentum of both balls are the same d) the change in momentum of both objects is zero I know the answer is a), but I don't understand how it is. Thanks.