Precise Reasoning Using "The Models" A) Think and Discuss: Imagine this situation: A string connecting a smaller mass, m, and a larger mass, M, passes over a small pulley that is almost frictionless. The masses are initially held at rest; then are released and allowed to move. Based on your intuition which set of attached masses (each differing by 20 g) will move faster when released? Set A: MA = 220 g, mA = 200 g Set B: MB = 70 g, mB = 50 g m Circle your choice here: Set A faster Set B faster Both the same smaller the weights , more the velocity of it Put your group's choice on the board. going Supp Try it out: Your TA will demonstrate this situation. What did you observe? 1/2 v2 ( Mtm ) = gh (M-m) V 2 = 2gh ( M-m ) Whole Class Discussion Mtm APEN + AKEM + APEm + AREm 2gh ( M - m ) B) Apply the Energy-Interaction Model: - Mgh + 16 Must mah + 1/ mve = 0 ( M + m ) 12 Muz + 1/ muz = Mgh - mah Apply the energy-interaction model to the two-masses-over-a-pulley situation. Model this system as if the pulley is massless and frictionless, so you won't have to worry about energies associated with the pulley. Take the initial state to be just as you release the masses (what is vi?). . Take the final state to be when the masses have moved a distance d and have some speed v, but