1. The problem statement, all variables and given/known data A cart on a level air track is being pulled by a force of weights attached to it by strings on a pulley system at the end of the air track. We know that an air track isn't completely frictionless, so in my calculations during experimentation, how would I account for that small amount of friction using the pulley system or anything else available to me? (I only have the air track, the pulley, and the weights.) 2. Relevant equations F = ma, kinematic formulas 3. The attempt at a solution We haven't learned about friction yet, but our lab professor wants us to take it into account anyway. Not sure how friction exactly works or what it exactly is, aside from the common sensical definition in that there is slight drag or resistance on the air track since there is actually air supporting the cart, and since air creates friction, we know that some amount of friction exists. But not sure how to calculate that into the lab.