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Torque. Tough Nut. Which of the four arrangements is best for tightening a bolt?. A. B. C. D. Pivot Point. Rotation of a wheel or wrench takes place with an axis of rotation. The point where the axis intersects the object is the pivot point. q. q. r. pivot point. Lever Arm.
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Tough Nut • Which of the four arrangements is best for tightening a bolt? A B C D
Pivot Point • Rotation of a wheel or wrench takes place with an axis of rotation. • The point where the axis intersects the object is the pivot point. q q r pivot point
Lever Arm • The tangential force acts at a distance away from the pivot point. • The distance from the pivot to the force is called the lever arm, or moment arm. lever arm points out from the pivot r
Perpendicular Component • Only the perpendicular component of the force can affect the tangential acceleration. • For an angle (q) between the force (F) and lever arm (r), the perpendicular component is Fsinq. angle between lever arm and force q
Moment of Force • The force exerted on the lever arm is the moment of force. • This is called torque (t).
Changing a Tire • A wheel nut needs 95 N-m of torque. • A 45 cm wrench makes a 67° angle with the horizontal. • The horizontal force needed: 113° 67° r
Torque Wrench • Consider the product rFsinq. rF (0.7)2rF = (1.4)rF (0.87)rF (3r/2)(F/2) = (3/4)rF next