exam2ws03sol - I: Last name initial Winter 2003 Last Name...

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Unformatted text preview: I: Last name initial Winter 2003 Last Name Physics 175 Exam #2 First Name ID # Points for each question are indicated in parentheses. Show your work for solutions to questions that require calculations. Explain from where you start to solve the problem and show your math flowing from it for full credit. Surround your result in a box and don ’t forget to include the units for your result. If you need more space to finish a question, write BPP (Back of the Previous Page) at the end of the space provided and then complete your work on the back of the previous page. For multiple choice questions, circle the letter which you believe to be correct (or best). In all problems, take the gravitational acceleration g = 10 m/sz. Problem 1 (5 points) You are pushing a wooden crate across the floor at constant speed. You decide to turn the crate on end, reducing by half the surface area in contact with the floor. In the new orientation, to push the same crate across the same floor with the same speed, the force that you apply must be about a) Four times as great :Fowc E 03" (Eva/k 0km &©€r> \Nb‘it‘“ (£61?ng 5 . b) Twice as great @ Equally great (Dm we: gm C6... d) Half as great e) One-fourth as great Problem 2 (15 points) A 1.5 kg block is initially at rest on a horizontal frictionless surface when a horizontal force in the positive direction of an x axis is applied to the block. The force is given by F (x) = (4 — x2)i in N, where X is in meters and the initial position of the block is x = 0. a) What is the kinetic energy of the block as it passes through x = 1 m? W2: AK :9) WT“ ky’ggk? 1 b) What is the maximum kinetic energy of the block between X = 0 and X = 3 m? x Aim! Wm: i mam "K . P 1F; 2 2:, :- a wee «A Q Qamli :3 Problem 3 (5 points) Two cars, starting from rest at the same place, travel by different routes to the same destination. One of the cars passes the other as they drive through it. Which of the following statements will be true? a) The work done by friction during the trip was the same for both b) The total work done on both is the same @ The work done by gravity is the same on both d) The work done by gravity on both is positive Problem 4 (26 points) A stone with mass m = 8 kg is at rest on top of a vertical spring. The spring is compressed 10 cm by the stone. a) Draw a free body diagram for the system and determine the spring constant, k. “M3? A «a; fiawq “*0 to C X‘O'”"d x .a M a b) The stone is pushed down an additional 30 cm and then released. What is the elastic potential energy of the spring just before that release? 1 K UR: 12k ($665; . u :i WW6 c) After being released, what is the speed of the stone when it‘leaves the spring (the spring is at equilibrium)? 2» a EA: 1&3 = a: w: «0+3\ac..&wa;§ infill, Egsz-i of): 3%; + Wigwam i ’ 2,, '2 “4 Ufo‘j”; A 3 QMQMMD) : £W%* WSWMU m—w—g v in 6H :i'guflé Jr 32 :3 34:: gkfizzgl’é d) What is the maximum height that the stone will reach after being released? Wham 3&“3, 5:00.61 \T‘Eiitidxfié) V\A..Cx><i um. um Mex: wB : l. \ddfidgf EA: EL EN Q. \N EC: KJU 7’ 9*“ “8’ r 2 a» imam; : Wish Problem 5 (5 points) During the lectures, prof. Kosztin made mistakes. To make up for all the times that she has made a mistake, she decided to give you an easy question, so here it is. What is the first letter of her first name? @A D c) ‘@ d) X e)K Problem 6 (5 points) A woman runs up a flight of stairs. The gain in her potential energy is U. If she runs up the same flight of stawith twice the speed, what will be her gain in potential energy? U b) 2U c) U/2 d) 4U e) U/4 Problem 7 (16 points) During the Great Muffin Wars of ’98, students from rival residences became familiar with the characteristics of various muffins. Mushy Pumpkin Surprise, for example, was good for temporarily blinding an attacker, while Mrs. O’Brian’s Muffins, having a higher density, were used mainly as a deterrent. According to the rule,eyery muffin must have a mass of 0.3 kg. During one of the most memorable battles, a muffin moving to the right at 5 m/s collided with a muffin moving to the left at 2 m/s. Find the final velocities of the two muffins if the collision was perfectly inelastic. . ‘ \1‘ pm. t x. Use momma.ka GS \met‘x y jemilmm if L( (Ft; 2 (Fr mum; Dixxrecliw org “Askew Problem 8 (5 points) 3 An Olympic diver dives off the high-diving platform (point A). The magnitude 1 of his momentum will be a maximum at point C a) A A b) B c) C D W11 Bonus Question (5 points) A block of wood is struck by a bullet. Is the block more likely to be knocked over if the bullet is metal and embeds itself in the wood, or if the bullet is rubber and bounces off the wood? Explain. The Wale. will lac- Wmfied ®\r€.\l Al Aim inorle {a \C \ID\/h€\r owl \vawfig 0&% We. mood, We dummy, U‘ . . . \ \ - “Hp. wow €1.%5\§%:'\.\\5\/x AW JAMS cage wot)?“ sue t: d5", ' a . a Gymkr «2.5) (twee. as. cg: Belle. 5:" , ...
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This note was uploaded on 04/30/2008 for the course PHYS 2760 taught by Professor Kozstin during the Spring '08 term at Missouri (Mizzou).

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exam2ws03sol - I: Last name initial Winter 2003 Last Name...

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