1. "Physics is like sex: sure, it may give some practical results, but that's not why we do it." -Richard Feynman

5. Which force applies a torque about the center of mass? A] weight B] static friction C] normal force D] weight and friction E] all three do If there were no friction at all, the hoop would accelerate A] faster B] slowerC] the same Comparing the two cases (no slipping vs. no friction); In which case would the total kinetic energy at the bottom of the hill be larger? A] no slippingB] no frictionC] K would be same

6. When a hoop rolls uphill without slipping, the direction of the frictional force is A] uphillB] downhillC] need more info to tell

7. If the rope is massless, but the pulley is NOT, are the tensions the same? A] yes, they are the sameB] T 2 >T 1 C] T 1 >T 2 Note: The rope does NOT slip over the pulley; there is enough friction to turn the pulley.