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Calculating torque (1) Choose a sign convention (e.g. anti-clockwise +ve), then decide in which direction force is pulling or pushing lever. Write that sign in front of your answer. Method 1: If you're given r and θ, use formula for torque (magnitude) τ = r F sinθ (Note: sinθ = sinφ, ∴ it doesn’t matter which angle you use)
Describe how the magnitude of a torque depends on the magnitude of the lever arm and the angle the force vector makes with the lever arm; Determine the sign (positive or negative) of a torque using the right-hand rule; Calculate individual torques about a common axis and sum them to find the net torque
LEVER ARM: The lever arm is the perpendicular distance from the axis of rotation to the line of action. Finding the lever arm is usually one of the hardest parts of torque problems. Start by finding ‘r’, which is the distance from the axis of rotation to the point where the force is applied.
14 Απρ 2021 · As the angle of the line of action changes, then the length of the 'lever arm' changes. In general... Either way you set it up, the torque is still given by the force applied, times the distance away from the pivot point, and the sine of the angle
Find the lever arm (or moment arm) by extending the line of the force and drawing a line from the axis of rotation so that is crosses the line of the force at a right angle. Finding the lever arm is often the most difficult part of a torque problem. Work done by a torque The expression for the work done is WT T W ' ¸ ' ¹ · ¨ © § A r r W F s
Torque is the rotational equivalent of a force. It is a measure of the effectiveness of a force in changing or accelerating a rotation (changing the angular velocity over a period of time). In equation form, the magnitude of torque is defined to be. τ = rF sin θ.
NOTE: here the lever arm = (force position - axis position). If signs are carefully kept, the sign of the force times the lever arm sign will successfully give the sign of the resulting torque.
