Physics test

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 points  

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

5 points  

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?

5 points  

Question 4

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

5 points  

Question 5

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

5 points  

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?

5 points  

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.

5 points  

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?

5 points  

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.

5 points  

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

5 points  

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  

5 points  

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  

5 points  

Question 13

The figure shows a uniform, horizontal beam (length = 10 m, mass = 25 kg) that is pivoted at the wall, with its far end supported by a cable that makes an angle of 51° with the horizontal. If a person (mass = 60 kg) stands 3.0 m from the pivot, what is the tension in the cable?    

2 points  

Question 14

Show your work for the above problem.

18 points  

Question 15

The graph shows a vertical position vs time plot of a 0.5 kg mass oscillating on a spring. Find the properties of this oscillator.

  a.            The amplitude Blank 1 b.            The period Blank 2 c.             The frequency Blank 3 d.            The spring constant Blank 4 e.            The maximum velocity Blank 5 f.             The maximum acceleration Blank 6 g.            The maximum force Blank 7

7 points  

Question 16

Show your work for the above problem.

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