qz9sol_0132Hf10 - external forces are exerted on the...

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TA: Tomoyuki Nakayama Monday, November 1, 2010 PHY 2048: Physic 1, Discussion Section 0132H Quiz 9 (Homework Set #10) Name: UFID: Formula sheets are not allowed. Calculators are allowed. Do not store equations in your calculator. You need to show all of your work for full credit. ________________________________________________________________________________ In the figure below right, a 80.0 kg uniform square sign, of edge length L = 2.50 m, is hung from a horizontal rod of length d h = 4.00 m and negligible mass. A cable is attached to the end of the rod and to a point on the wall at distance d v = 6.00 m above the point where the rod is hinged to the wall. a) What is the tension in the cable? The angle between the cable and the rod is θ = tan -1 (d v /d h ) = 56.3º We consider the system which consists of the rod and square sign. Four
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Unformatted text preview: external forces are exerted on the system: Gravitational force at the center of the sign, tension in the cable, and x and y components of the force from the hinge. Choosing our rotational axis at the hinge, we apply the balance of torques equation to get the tension. Tsin θ d h – mg(d h – L/2) = 0 ⇒ T = mg(d h – L/2)/(sin θ d h ) = 648 N b) What are the horizontal and vertical components of the force on the rod from the wall? Take the positive directions to the right and upward respectively. We take our +x axis to the right and +y axis upward. The balance of forces equations yield x: F x – Tcos θ = 0 F x = Tcos θ = 360 N y: F y + Tsin θ – mg = 0 F y = mg – Tsin θ = 245 N...
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This note was uploaded on 01/25/2011 for the course PHY 2048 taught by Professor Field during the Summer '08 term at University of Florida.

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