Quiz_5_120407_answer - Explicit the magnitude and the...

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Physical Science 303 Quiz #5 , Dec. 04 2007 Name : 1. It is specified that a certain nut be tightened to a torque of 40 Nm. If the mechanic is using a 40cm long wrench, how much force must he apply to the end of the wrench to meet specs? (10pts) 40 Nm = 0.4m x F, F=40 Nm / 0.4m = 100 N 2. There are three forces acting on an object on a frictionless table. The force are : 5N East, 4N West, and 10N North. (10 pts) a) Find the resultant force in rectangular coordinate . ( 1N , 10N ) b) Is the object in equilibrium and why or why not? NO because the net force is not zero. 3. Write down two conditions for equilibrium. (5pts) 1) the net force is zero 2) the net torque is zero
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4. Two forces (F1 and F2) are exerted on the wooden rod whose one end is fixed and the other end is freely rotating. The magnitude of F1 is 30N and the distance from the rotating axis is 0.4 m, and 15N , 1.2 m are for F2. (15pts) (1) Calculate the torque on the rod from the force F1. Express answer in Nm.
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Unformatted text preview: Explicit the magnitude and the direction of the torque. (4pts) Torque1 = 0.4 m x 30 N = 12Nm Direction : counter clockwise (2) Calculate the torque on the rod from the force F2. Express answer in Nm. Explicit the magnitude and the direction of the torque. (4pts) Torque2 = 1.2 m x 15 N = 18Nm Direction : clockwise (3) If another force ( F3 ) would be applied to the position 0.8m away from the rotating axis to make the rod equilibrium, which way of the direction F3 should be? Up or Down? (3pts) Up : In order to make it in equilibrium, the net torque should be zero. Torque1 + Torque2 is clockwise direction (Torque2>Torque1). We need counter clockwise torque. (4) Calculate the magnitude of F3. (4pts) Torque1 + Torque2 + Torque3 = 0 12Nm -18Nm + Torque3 =0, Torque3 = 6Nm, F3=Torque3/0.8m = 7.5N...
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This note was uploaded on 04/29/2008 for the course PS 303 taught by Professor Modi during the Spring '08 term at University of Texas at Austin.

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Quiz_5_120407_answer - Explicit the magnitude and the...

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