p140f04_final_1_sol

# p140f04_final_1_sol - Physics 140 Fall 2004 Final Exam...

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1. A monkey whose mass is “m”, hangs from a rope which stretches over a pulley to an equal mass bunch of bananas hanging from the other end as shown in the left hand picture. Another (identical) monkey jumps onto the bananas. What is the magnitude of the acceleration experienced by each monkey for this newly unbalanced case (shown on the right)? (a) 0.66g (b) 1.33 g (c) 0.66 g (d) *0.33 g (e) 0.5 g 2. A block of mass m 1 is pulled along a frictionless horizontal surface by another block connected to it by a rope as shown below. What is the acceleration of block m 1 ? (a) (m 1 /m 2 )g (b) m 2 g/(m 1 -m 2 ) (c) g (d) m 1 g/(m 1 +m 2 ) (e) *m 2 g/(m 1 +m 2 ) m 1 m 2 In the new unbalanced case you have 2m on the right, and m on the left. Sum the forces on each: Σ F l = T – mg = ma, Σ F r = 2mg – T = 2ma. Adding these two equations, you obtain mg = 3ma, or a = g/3. Σ F 1 = T = m 1 a Σ F 2 = m 2 g – T = m 2 a Adding these equations m 2 g = (m 1 + m 2 )a a= m 2 g / (m 1 + m 2 )
3: A block of mass M is attached to a cord that is wrapped around the rim of a pulley of diameter 50 cm and hangs vertically as shown. The rotational inertia of the pulley is 0.4 kgm 2 . When the block is released the cord unwinds and the acceleration of the block is 6.4 m/s 2 . What is the mass of the block? (a) 1 kg (b) 3 kg (c) 6 kg (d) 10 kg (e) *12 kg 4: A pool ball of mass m , initially at rest, is struck by a cue stick so that it acquires a speed v. If t represents the duration of the collision between the stick and the ball, which expression determines the magnitude of the average force exerted on the ball? (a)

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## This homework help was uploaded on 04/04/2008 for the course PHYSICS 140 taught by Professor Evrard during the Fall '07 term at University of Michigan.

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p140f04_final_1_sol - Physics 140 Fall 2004 Final Exam...

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