Hi, 1. The problem statement, all variables and given/known data I have three elementary questions and would appreciate feedback on my attempt at answering them. Thanks in advance! (1) Will the laws of conservation of energy be accurately preserved in the lab? (2) When pushing a cart across a surface, how can energy losses due to friction be compensated for? (3) When a weight and a cart are tied together by means of an inelastic cord through a set of 3 pulleys, what would be the relation between their movements? What would be the relation between their velocities? Which component will be preserved in this setup? 3. The attempt at a solution (1) I think they wouldn't "accurately" be conserved, as there will always be loss of energy due to friction, gravitation, etc. to heat and other forms. (2) I think tilting the cart, thus reducing the effective surface area, should make it easier. Moreover, the wheels could, for instance, be coated with rubber or some other material which would reduce the friction, though I am not sure that's what the question aimed at. (3) I think the cord's length will be preserved in this setup and since it is inelastic the displacement of the cart and weight, including their velocities and acceleration, will all be the same.