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Question
The adjacent diagram shows a heavy roller, with its axle at O, which is to be raised on a pavement XY. If there is friction between the roller and pavement, show by an arrow on the diagram the point of application and the direction of force to be applied. If pivoted at O, now will it go up?
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Solution
The force should be applied at the topmost point of the roller. The direction of the force should be perpendicular to the axle O and upward at an angle, to generate torque. If the roller is pivoted at O, it will not go up because the applied force at O does not generate enough torque to lift the roller against gravity and friction.
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