Newton's 2nd Law Lab: Keeping Mass Constant?

[Ally385]

Homework Statement

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?

Homework Equations

a=f/m

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!

 

[PeterO]

Homework Statement

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?

Homework Equations

a=f/m

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!

How were you "generating" the force? If you were hanging the masses on a string over the pulley - then those masses were also accelerating; changing the over all mass being accelerated.

For example, if you drop a 1 kg cart, it will begin to accelerate at g, like anything else you drop.

If you hang a 2kg mass on a string over a pulley, you might think it generates a force twice the weight of the 1 kg cart. That could lead you to expect an acceleration of 2g. Will that 2g acceleration really happen?