Calculating Force for Torque: Understanding Proper Spark Plug Tightening

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1. You are installing a new spark plug in your car, and the manual specifies that it be tightened to a torque that has a magnitude of 26 N·m. Using the data in the drawing, determine the magnitude F of the force that you must exert on the wrench.



2. Torque= Force * Lever arm length



3. The force is said to be 26 N*m, and the lever arm length is shown to be 0.28 cm in the picture.

26 N*m = F * 0.28 m
F= 26 N*m/0.28m
F= 92.86 N

Which is wrong. What did I do wrong?
 
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  • Diagram of a torque wrench on a spark plug, with a 0.28 m lever arm drawn from the pivot to the handle, a 50.0° angle marked, and force F shown as an arrow at the tool.
    Torque 1.gif
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0.28 is the length of it, not the perpendicular distance. What is the perpendicular distance it nust move?
 
IAmSparticus said:
Is it 16.165 cm (.16165 m)?

How did you get that?

The wrench forms a right angled triangle with hypotenuse 0.28 which makes an angle of 50 with the horizontal.