exam 2 fall 2008

# exam 2 fall 2008 - QUESTION 1* This and the next three...

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QUESTION 1* This and the next three questions refer to the following situation: A block m 1 with mass 7 kg moves up an inclined plane with an initial velocity v 0 = 4.7 m/s. The inclined plane is at an angle of θ = 45° from the horizontal. The coefficient of kinetic friction between the block and the incline is 0.25. What is the block's velocity when it has traveled a distance D=1 meter up the incline? (a) 0.10 m/s (b) 0.31 m/s (c) 0.57 m/s (d) 1.59 m/s (e) 2.18 m/s QUESTION 2* Traveling up the incline, the work done on the block by friction is: (a) - mgD sin θ (b) μ k mgD cos θ /2 (c) μ k mgD (d) - μ k mgD cos θ (e) mgD sin θ QUESTION 3* If mass m 1 is cut in half, the speed of the block when it has traveled D = 1 meter up the incline (a) decreases. (b) stays the same. (c) increases.

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QUESTION 4* If the initial velocity is doubled, the speed when it has traveled D = 1 meter up the incline has also doubled. (T) True (F) False QUESTION 5** This and the next two questions refer to the following situation: A frictionless ramp of mass 3 m is initially at rest on a horizontal frictionless floor. A small box of mass m is placed at the top of the ramp and then released from rest. After the box is released, it slides down the ramp and onto the horizontal floor, where it is measured to have a speed v , having fallen a total distance h . What is the speed v of the box after it has left the ramp? (a) (b) (c) (d) (e) QUESTION 6* If there were kinetic friction between the box and the ramp, but none between the ramp or block and the floor, the speed v of the box after it has left the ramp, compared to its speed when both the ramp and the floor are frictionless, would be (a) less than in the previous question. (b) the same as in the previous question. (c) more than in the previous question
QUESTION 7 THIS QUESTION WAS DISCARDED -- ANSWER "a" If there were kinetic friction between the ramp and the floor, but none between the box and the ramp, the speed v of the box after it has left the ramp, compared to its speed when both the ramp and the floor are frictionless, would be (a) less. (b) the same.

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## This note was uploaded on 05/04/2011 for the course PHYS 211 taught by Professor Liss during the Spring '08 term at University of Illinois at Urbana–Champaign.

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exam 2 fall 2008 - QUESTION 1* This and the next three...

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