Question

5. A hollow sphere, a solid cylinder, and a hollow cylinder are all released from rest at the top of a ramp. Which object reaches the bottom of the ramp first? (a) The hollow sphere (b) The solid cylinder (c) The hollow cylinder (d) They all reach the bottom of the ramp at the same time

6. What is the formula for the moment of inertia of a hollow cylinder rotating about an axis at its edge? (a) I = 1 2 MR2 (b) I = MR2 (c) I = 3 2 MR2 (d) I = 2MR2

7. A meter stick is held such that it rotates at its end. If the meter stick has a mass of 100g, how much torque does gravity produce? (a) 0 Nm (b) 0.5 Nm (c) 0.75 Nm (d) 1 Nm

8. A wheel is placed at the top of an incline. What force acting on the wheel produces the torque responsible for rolling the wheel down the incline? Hint: think about which point on the wheel acts as the axis when the wheel is rolling. (a) Gravity (b) Static friction (c) Kinetic friction (d) The normal force

9. An ice skater with her hands pulled in towards her body is going to have a smaller moment of inertia than with her hands outstretched. (a) True (b) False

Answer 1

5) Answer: b

The solid cylinder would reach faster as it has the least moment of inertia

6) Answer: d

Thus I = 2MR²

7) Answer: a

The torque due to gravity is zero

8) Answer: b

The static friction is responsible for the production of torque during rolling down an incline as at the point of contact there is no relative motion between the wheel and surface.

8) Answer: a

Since R is decreasing when hands are pulled in, the moment of inertia has to decrease too