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Homework Help: Torque Problem examples

  1. Apr 11, 2005 #1
    We just started torque and our teacher gave us some problems but we didn't do any examples. I have no idea where to start. Thanks for your help.

    The fishing pole in Figure P10.30(i drew a picture of it) makes an angle of 20 degrees with the horizontal. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the fishers hand?

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  3. Apr 12, 2005 #2


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    You need to find the component of the force exerted by the fish (the 100 N) that is perpendicular to the fishing pole. To do that, you have to look at the end of the pole and the two angles you are given. You will have your 100N force as the hypotenuse of a right triangle and you need to find the angle it makes with the pole.

    20° + 37° = 57°. That's not quite 90°. That means that the angle that is made by the force vector is 90-57 = 33°.

    Now that you know the angle that the force is at in relation to the pole, you have to get the component that is perpendicular, or in this case, the adjacent side of the triangle. The length of the adjacent side is going to be 100 N* cos 33° = 83.9 N.

    Now all you have to do is calculate the torque by taking the force and the distance to the hand, which in this case is T = (83.9N)*(2.0m) = 167.8 N*m.
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