# test14 - COE 2001 — Test 1 -— Spring 2007 Name: KEV...

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Unformatted text preview: COE 2001 — Test 1 -— Spring 2007 Name: KEV PLEASE NOTE: 1. If axes are speciﬁed for a given problem, you are to use them. Do not change them in any way or you get a 0 (zero) to that question. 2. Show all work. 3. If you make an assumption, state it clearly. 4. Provide units with your answers, and box them. 5. Use the back of the equation sheet as scrap paper if needed. 6. The “1b” unit means “lb-force” in this test, NOT “lb—mass” (i.e. do NOT multiply by gravity to get a force!). 7. Deﬁne clearly any new variable you introduce in a problem based on the givens. 8. For the second problem, you are to use vectors to solve it, i.e. write forces and moment arms as vectors and calculate moments using cross products. Failure to comply will result in a O to the question even it you arrive at the right answer in some dﬁerent manner. Pb. I (50 pts) — The bar ABC, with right angle at B, weighs 30 N with center of gravity at G. It is supported by a pin at A, a roller at C, and a cable at B, as shown in the picture below. 1. Draw a FBD of ABC alone. What angle does the reaction force at the roller make with the vertical (y axis)? ' 2. Draw a FBD for each pulley, and apply equilibrium based on the axes given. What is the tension in the cable at B? 3. Apply equilibrium to ABC and solve for the reaction forces at A and C. 4. Could you solve the problem if A was ﬁxed instead of pinned? Justify your answer in a couple of sentences. No math is needed to answer this question. +3 ZMA = K —30C0-4v) S": gene R? Ln Q) ~. A} 2 64.4») mg): 155’: _\3?.€M ____/ aﬁuimon'um aide” ' Pb 11 (50 pts) — The uniform 30— by 40-inch trap door weighs 150 lb and is propped open by the light strut _AB at the angle 9 = arc tan (4/3). We want to determine the compr ssion force F in the strut (ONLY). 1. Draw a FBD of the door only. Treat the hinges Agnd B’a ball—and—socket joints that are negligibly small and act at the extreme ends of the lower edge (line CD). For the door, which way is F oriented, up towards B or down towards A? Assume the center of gravity G of the door is its geometrical center (uniform mass). 2. Express F fully in terms of its components along the x, y, z axes as deﬁned in the picture. Calculate the moment of F at C, using vectors and cross—products, in terms of the unknown magnitude. 4. Do you need the 2 F = 0 equation to solve for the unknown force in this problem? Apply equilibrium and solve for the force in AB. 5” £11 y <1 CON/0) ...
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## This note was uploaded on 11/04/2009 for the course COE 2001 taught by Professor Valle during the Spring '08 term at Georgia Tech.

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test14 - COE 2001 — Test 1 -— Spring 2007 Name: KEV...

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