1. The problem statement, all variables and given/known data We did a lab in class where we had a cart and we had nothing on top of it. We added different forces at the end of a pulley to see how the acceleration differed with different forces. One of the questions on our lab was: We tried to keep the "mass constant". Why is this really not true? Does this affect our results significantly? How could this be resolved? 2. Relevant equations a=f/m 3. The attempt at a solution I can't think of any way that the mass would not be constant. Its not like we were leaning on the cart or anything. Thank you!