Quiz+8+Solution+Section+D

Quiz+8+Solution+Section+D - 7B.S11 Quiz 8D Last 6 digits of...

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7B.S11 - Quiz 8D DL SECTION _ Grade: 05/25/2011 No books or notes. Calculators OK. Show all your work below. Answers alone will receive no credit! This quiz has two sides! A horizontal beam with a lamp on the end is attached to a wall by a hinge. A rope is attached so as to keep the beam stationary. The lamp has a mass of 25 kg and the rope is attached to the beam at an angle of 60 degrees , as shown in the picture. The point where the lamp attaches to the beam is 2 m to the right of the hinge on the wall. Assume the beam is massless (in other words, you do not have to take into account the force of the earth on the beam). a) What is the net torque on the beam? What is the net force on the beam? Very briefly and clearly explain your reasoning. Since the center of mass of the beam is not moving and the beam is also not rotating, the linear and angular momentum are both not changing . Therefore the net force and the net torque on the beam must be zero. b) The force of the rope on the beam is known to have a magnitude of 1000 N (and pointing along the direction of the rope of course). Find the x and y components of the force of the hinge on the beam . (hint: find the x and y components of the force of the rope on the beam first; a force diagram may also be useful). There are three forces on the beam (rope, hinge and lamp). There is no force of Earth on the beam because the beam is massless. We know from part a) that the net force must be 0, so this will allow us to find the force of the hinge. The only forces with non-zero x-components are those of the rope and the hinge (the lamp force points

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This note was uploaded on 10/24/2011 for the course PHYSICS 7B taught by Professor Johnconway during the Spring '07 term at UC Davis.

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Quiz+8+Solution+Section+D - 7B.S11 Quiz 8D Last 6 digits of...

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