Posted by Steph on Wednesday, July 16, 2008 at 11:40pm.
A 3.0 m rod is pivoted about its left end.A force of 6.0 N is applied perpendicular to the rod at a distance of 1.2 m from the pivot causing a ccw torque, and a force of 5.2 is applied at the end of the rod 3.0 m from the pivot. The 5.2 N is at an angle of 30 degrees to the rod and causes a cw torque. What is the net torque about the pivot?
I don't have a clue how to even start this question.
physics class-Help!!! - drwls, Thursday, July 17, 2008 at 12:05am
Add up the torques about the pivot, treating counterclockwise torques as positive and clockwise as negative.
physics class-Help!!! - Steph, Thursday, July 17, 2008 at 7:59am
torque is radius X Force sin theta
Torque 1 and 2 have angles of 90 degrees making it equal to 1.
Torque 1:0.6 (radius of 1.2) X 6.0 N
Torque 2:1.5 (radius of 3)X 5.2 N
Torque 3:1.5 (radius of 3)X 5.2 N sine 30 degrees
Torque 1 + Torque 2 + Torque 3 = Net Torque
3.6 + 7.8 + 3.9 = 15.3
Is this correct?
physics class-Help!!! - drwls, Thursday, July 17, 2008 at 9:01am
No, it isn't, but thanks for showing your work. Actually there are only two torques applied. I don't see why you are applying a factor of 1/2 to each radius
Torque 1 is +1.2 x 6.0 = +7.2 N-m
Torque 2 is -3.0 x 5.2 sin 30 = -7.8 N-m
The net torque is -0.6 N-m
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