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