Question 1: An ice skater has a moment of inertia of 2.8kg*m^2 when her arms are outstretched and a moment of inertia of 1.0kg*m^2 when her arms are at her side. If she starts to spin at a frequency of 2 Hz with her arms outstretched, what will her frequency be when they are tucked in?

5.6 Hz

1.4 Hz

2.8 Hz

2 Hz

Question 2: A uniform solid disk of radius 7cm and mass 2kg starts from rest and accelerates uniformly under the action of a constant torque of 0.6 Nm. How long does the wheel take to reach its final operating speed of 1200 rev/min. The moment of inertia of a disk is 1/2 m r2.

0.23s

1.03s

8.57s

0.42

Question 3: A wheel with a moment of inertia of 20 kg m2 initially rotates freely with an angular velocity of 10 rad/s. A pad is applied to the outer surface to stop it. If it takes 10 seconds to stop, what is the torque due to friction?

20 Nm

2 Nm

100 Nm

5 Nm

Question 4: The angular position of a point on a wheel is described by When does the wheel reverse direction?

25s

4s

2s

0.25s

Question 5: What is the magnitude of the angular momentum of a 2kg particle described by the following velocity and postion vectors?

2 kg m2/s

28 kg m2/s

0 kg m2/s

14 kg m2/s

Question 6: A hydraulic lift raises a 2 000-kg automobile when a 500-N force is applied to the smaller piston. If the smaller piston has an area of 10 cm2, what is the cross-sectional area of the larger piston?

40 cm2

80 cm2

196 cm2

392 cm2

Question 7: A blimp is filled with 200 m3 of helium. How much mass can the balloon lift? The density of helium is one-seventh that of air, and the density of air is 1/800 that of water. Consider the mass of the balloon to be negligible.

115 kg

214 kg

315 kg

415 kg

Question 8: Water pressurized to 3.5 × 105 Pa is flowing at 5.0 m/s in a horizontal pipe which contracts to 1/3 its former area. What are the pressure and velocity of the water after the contraction?

2.5*105 Pa, 15 m/s

3.0*105 Pa, 10 m/s

3.0*105 Pa, 15 m/s

4.5*105 Pa, 1.5 m/s

Question 9: A fountain sends water to a height of 100 meters. What must be the pressurization (above atmospheric) of the water system? 1 ATM = 1.01 × 105 N/m2.

1.0 ATM

4.2 ATM

7.2 ATM

9.7 ATM

Question 10: A body oscillates with simple harmonic motion along the x axis. Its displacement varies with time according to the equation x = 5.0 cos (πt). The magnitude of the acceleration (in m/s2) of the body at t = 1.0 s is approximately

3.5

49

14

43

Question 11: A mass m = 2.0 kg is attached to a spring having a force constant k = 290 N/m as in the figure. The mass is displaced from its equilibrium position and released. Its frequency of oscillation (in Hz) is approximately

12

0.50

0.010

1.9

Question 12: A uniform rod (mass m = 1.0 kg and length L = 2.0 m) pivoted at one end oscillates in a vertical plane as shown below. The period of oscillation (in s) is approximately

4.0

1.6

3.2

2.3