Interpreting Rotational Motion and Torque Diagrams

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AP Physics C: Electricity and Magnetism › Interpreting Rotational Motion and Torque Diagrams

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A mechanic is using a wrench to loosen and tighten screws on an engine block and wants to increase the amount of torque he puts on the screws to adjust them more easily. Which of the following steps will not help him to do so?

Pulling or pushing at an angle that is less perpendicular to the wrench

Using a longer wrench

Increasing the magnitude of the force he puts on the wrench

Pulling or pushing at an angle that is more perpendicular to the wrench

Using a wrench of a different material

Explanation

Remember the torque equation:

$\tau = ||r|| * ||F|| * \sin \theta$

Exerting force on the wrench at an angle less perpendicular to the wrench will reduce $\sin \theta$ and thus reduce the torque.

The other answer options will all increase the torque being applied, making the twisting motion easier.

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