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Unformatted text preview: University of Minnesota Name: School of Physics and Astronomy Student ID No: Physics 1301, Section 200, Fall 2008 TA Name: Hour Exam 2: Problem 1 (Friday, October 10, 2008) [Please do the problem on the front and back of this sheet of paper.] A typical sailboat has two sails attached to a mast or pole that rises from the deck of the sailboat. The mast is typically stabilized with two stainless steel wires. The forestay goes from the deck near the front of the boat to the top of the mast. The backstay goes from the deck near the back of the boat to the top of the mast. For this problem, you should use the following dimensions. The distance between the deck attachment of the forestay and the backstay is 10.0 m. The mast is 12.0 m in length, has a weight of 800. N and rises vertically from the deck. The base of the mast is positioned 3.60 m behind the attachment point of the forestay to the deck. The tension in the forestay is 500. N. (a) Draw and label (with distances and angles) a diagram showing the deck of the boat, the mast, the forestay and the backstay. (5 points) (b) Draw and label a free body diagram showing the forces at the top of the mast. (5 points) (c) What is the magnitude of the horizontal component of the tension in the backstay? (5 points) (d) What is the total magnitude of the tension in the backstay? (5 points) (e) What are the magnitude and direction of the force that the mast exerts on the deck? (5 points) University of Minnesota Name: School of Physics and Astronomy Student ID No: Physics 1301, Section 200, Fall 2008 TA Name: Hour Exam 2: Problem 2 (Friday, October 10, 2008) [This problem is similar to the "Optional Homework Problem", Chapter 5, Problem 34. Please do the problem on the front and back of this sheet of paper.] A roof has a slope of 45.0 to the horizontal. The distance along the roof from the crest to the edge is 6.00 m. A pile of snow at the crest of this roof starts to slide off. The coefficient of kinetic friction between the snow and the roof is 0.150. (a) How long does it take the snow to slide from the peak of the roof to the edge? (5 points) (b) What is the velocity of the snow at the edge of the roof? (5 points) (c) If the edge of the roof is 6 m vertically above the ground, how long does it take the snow to fall to the ground, once it leaves the edge of the roof? (10 points) (d) How far horizontally from the wall below the edge of the roof does the snow land when it hits the ground? [5 points] University of Minnesota School of Physics and Astronomy Physics 1301, Section 200, Fall 2008 Hour Exam 2: Multiple Choice (Friday, October 10, 2008) [Please mark the answers to the problems below on the bubble sheet. Each question is 5 points.] 1. A force exerted by a stretched rubber band produces an acceleration of 5.0 m/s2 on a block with a mass of 1.0 kg. A similar rubber band stretched by the same amount produces an acceleration of 11 m/s2 on a second block. What is the mass of the second block? (a) 0.35 kg (b) 0.45 kg (c) 0.75 kg (d) 1.0 kg (e) 1.2 kg 2. A 110.0 kg basketball player hanging on the basket rim deflects the rim by 15.0 cm. Assume that the rim acts as a spring that obeys Hooke's Law. What is the spring constant for the rim? (a) 2.5 x 103 N/m (b) 4.3 x 103 N/m (c) 5.6 x 103 N/m (d) 7.2 x 103 N/m (e) 8.4 x 103 N/m 3. A picture frame weighing 8.0 N is supported from the ceiling by two wires. The two wires are attached to the picture frame at a single point. Wire 1 is attached to the ceiling to the left of the picture frame. The angle between the ceiling and Wire 1 is 60. Wire 2 is attached to the ceiling to the right of the picture frame. The angle between the ceiling and Wire 2 is 30. What is the tension in Wire 1? (a) 4.0 N (b) 5.7 N (c) 6.9 N (d) 7.5 N (e) 8.0 N 4. You pull two children sitting on a sled using a rope that makes an angle of 40 to the horizontal. The children have a combined mass of 45.0 kg and the sled has a mass of 5.00 kg. The coefficient of kinetic friction is 0.15. What is the acceleration of the sled if the force on the rope is 140 N? (a) 0.32 m/s2 (b) 0.48 m/s2 (c) 0.61 m/s2 (d) 0.78 m/s2 (e) 0.94 m/s2 5. Which of the following statements are true? I. The force required to make an object travel in a circle is proportional to the first power of the angular velocity of the object. II. The force required to make an object travel in a circle is proportional to the mass of the object. III. The force required to make an object travel in a circle is proportional to the first power of the linear velocity of the object. (a) Statement I only. (b) Statement II only. (c) Statement III only. (d) Statements I and II only. (e) Statements II and III only. ...
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 Fall '08
 Marshak
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