All science is either physics or stamp collecting. - Ernest Rutherford ( ) Discoverer of the nucleus

A car goes around a banked curve that is icy (frictionless). The centripetal force is: A] absent (not needed) because of the banking B] the component of gravity acting toward the inside of the curve C] the component of the normal force acting toward the inside of the curve D] A combination of B&C

A greasy (frictionless) hand pushes two blocks against a vertical wall. There is static friction, coefficient , between the blocks and with the wall. You wish to find out the minimum pushing force to keep the blocks from slipping. Take out a pencil and paper, and draw the required FBD(s). Which arrows show the directions and relative magnitudes of the frictional forces on Block 2?

Which curve could describe the (1D) velocity of a block sliding down an inclined plane, as a function of time? Which curve could describe the (1D) velocity of a skydiver, as a function of time? Fluid Resistance A B C Any answer accepted. B is Best. C

Assume the rate a car burns gas (in gallons/minute) is proportional to the force the engine applies to the road (through the tires, of course.) How much faster do you burn gas at a steady 80 mph vs at 40 mph? Assume all resistance is air resistance. A] You don’t burn gas because v is steady B] Same rate per minute C] Twice as fast D] Four times as fast E] Sixteen times as fast Answer: D, since resistance increases with the square of velocity. Note: your gas mileage would be half at 80 mph as at 40 mph. Why?

Forces acting on two particles are shown. The forces are constant during the displacements shown. Which force does no work? A] F 1A B] F 2A C] F 1B D] F 2B E] They all do work For which particle is the total work done by all forces = 0? Choose A, B, or C both=0. A

Bonus Question: If the forces shown are the only forces acting on the particles, which particle will change speed? B will change its speed and velocity!