Please Note: It may not always be possible to include the necessary special characters, superscripts, subscripts, etc. in e-mail responses to this group of exercises. We suggest that you discuss this matter with your professor/class and decide upon a system for indicating such characters. You may cut/paste some characters and/or Greek letters from Microsoft Word, using the Insert menu. Alternatively, we suggest that you agree upon abbreviations for or spell out symbols, Greek letters, or characters and indicate superscripts and subscripts by using "sup", "sub", or up/down carats.

h = height from which putty is dropped ω i = initial angular speed r = radius of disk m = mass of putty = mass of disk

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Determine the following:

1			The initial moment of inertia of the rotating disk Need a Hint?
2			The initial angular momentum of the rotating disk Need a Hint?
3			The initial kinetic energy of the rotating disk Need a Hint?
4			The moment of inertia of the putty after it is dropped onto the disk Need a Hint?
5			The final moment of inertia of the rotating system (disk and putty) Need a Hint?
6			The final angular momentum of the rotating system (disk and putty) Need a Hint?
7			The final angular speed of the rotating system (disk and putty) Need a Hint?
8			The final kinetic energy of the rotating system (disk and putty) Need a Hint?
9			The change in the kinetic energy of the rotating system as the putty falls onto the disk Need a Hint?
10			What happened to this decrease in kinetic energy Need a Hint?

A rigid body of irregular shape is mounted on an axle of radius r and negligible mass, as shown below. A string is wrapped around the axle, and a block of mass m is attached to it. The system is released from rest, and the block descends a distance h in a time t. Note: The center of mass of the irregular shaped object is at the center of rotation.

m = mass of block r = radius of axle t = time block takes to descend the distance h h = distance block descends in time t g = acceleration due to gravity

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11			The final linear speed of the block (that is, its speed after it has fallen the distance h) Need a Hint?
12			The final angular speed of the rigid body Need a Hint?
13			The final translational kinetic energy of the block Need a Hint?
14			The decrease in gravitational potential energy of the block as it descends the distance h Need a Hint?
15			The final rotational kinetic energy of the rigid body Need a Hint?
16			The moment of inertia of the rigid body obtained by using energy principles Need a Hint?
17			The linear acceleration of the block Need a Hint?
18			The angular acceleration of the rigid body Need a Hint?
19			The tension in the string that supports the block Need a Hint?
20			The torque tending to rotate the rigid body Need a Hint?
21			The moment of inertia of the rigid body obtained by using torque principles Need a Hint?
22			Average power delivered to the rotating system by the gravitational force Need a Hint?

A sign is suspended from a uniform pole as shown. The pole is attached to the wall by means of a bracket and pin.

Ws = 500 N = weight of the sign Wp = 200 N = weight of the pole  L = 4.00 m = length of the pole

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23			Torque about pin P due to the weight of the sign Need a Hint?
24			Torque about pin P due to the weight of the pole Need a Hint?
25			Torque about pin P due to cable 2 Need a Hint?
26			The tension in cable 2 Need a Hint?
27			Horizontal component of the force that pin P exerts on the pole Need a Hint?
28			Vertical component of the force that pin P exerts on the pole Need a Hint?

A disk is mounted in a frictionless manner on an axle as shown. Components of the forces and position vectors are given below.		<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0070524076/57991/ch8_img4.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (2.0K)</a>
F1x = -10 N F1y = 0 r1x = 4 m r1y = -3 m	F2x = 0 F2y = -8 N r2x = -2 m r2y = 3m

29			Magnitude of the torque due to F1 Need a Hint?
30			Direction F1 tends to rotate the disk Need a Hint?
31			Magnitude of the torque due to F2 Need a Hint?
32			Direction F2 tends to rotate the disk Need a Hint?
33			Net torque acting on the disk Need a Hint?
34			Direction of rotation of the disk Need a Hint?