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slipping occurs.  (b) What is the final angular speed of a tire in revolutions per second?

17.A disk 8.00 cm in radius rotates at a constant rate of 1 200 rev/min about its central axis. Determine (a) its angular speed, (b) the tangential speed at a point 3.00 cm from its center, (c) the radial acceleration of a point on the rim, and (d) the total distance a point on the rim moves in 2.00 s.

18.A car traveling on a flat (unbanked) circular track accelerates uniformly from rest with a tangential acceleration of

1.70 m/s2.  The car makes it one-quarter of the way around the circle before it skids off the track.  Determine the coefficient of static friction between the car and track from these data.

19.Consider a tall building located on the Earth’s equator.  As the Earth rotates, a person on the top floor of the building moves faster than someone on the ground with respect to an inertial reference frame, because the latter person is closer to the Earth’s axis.  Consequently, if an object is dropped from the top floor to the ground a distance h below, it lands east of the point vertically below where it was dropped.  (a) How far to the east will the object land?  Express your answer in terms of h, g and the angular speed of the Earth.  Neglect air resistance, and assume that the free-fall acceleration is constant over this range of heights.    (b) Evaluate the eastward displacement for h = 50.0 m.  (c) In your judgment, were we justified in ignoring this aspect of the Coriolis effect in our previous study of free fall?

Section 10.4  Rotational Kinetic Energy

20.Rigid rods of negligible mass lying

along the y axis connect three particles (Fig. P10.20). If the system rotates about the x axis with an angular speed of 2.00 rad/s, find (a) the moment of inertia about the x axis and the total rotational kinetic energy evaluated from and (b) the tangential speed of each particle and the total kinetic energy evaluated from


Figure P10.20

21.The four particles in Figure P10.21 are connected by rigid rods of negligible mass. The origin is at the center of the rectangle. If the system rotates in the xy plane about the z axis with an angular speed of 6.00 rad/s, calculate (a) the moment of inertia of the system about the z axis and (b) the rotational kinetic energy of the system.

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