Q8_7B_W10 - vectors with their tails at the point where the...

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Name: , DL Section: Last First Office Use Quiz 8 Physics 7B Winter 2010 Mar. 03, 2010 Consider an Atwood machine that has two unequal masses ( m 1 = 10 kg and m 2 = 5 kg) a pulley with radius R = 10 cm and mass M = 10 kg, and a massless string that can not stretch. The moment of inertia of the pulley is I = ½ MR 2 . The bearing about which the pulley rotates is frictionless. a) The two masses are released, and because m 1 > m 2 , m 1 starts to descend, while m 2 rises, and the pulley wheel starts to rotate. After some period of time, m 1 has a downward speed of v = 1 m/s. What is the angular velocity of the pulley (magnitude and direction). b) Consider a moment in time (different from part a) when = 5 rad/s. What net angular impulse had to be provided to bring the pulley from rest to 5 rad/s? c) On the diagram above, draw in all the force vectors acting upon the pulley. Draw the force
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Unformatted text preview: vectors with their tails at the point where the force is applied, and their arrows in the direction of the force. The length of the force vectors should represent to relative magnitudes of the forces (accuracy counts). d) Often in pulley problems we assume that the tension in the string is uniform throughout the length of the string. This is not the case in this problem. Explain why the tension in the string pulling up on m 1 is not equal in magnitude to the tension pulling up on m 2 . r v t P r L I L 2 2 1 I KE rot F r t L Object on Net L J Ang dt I dt L d...
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