Torque
Tough Nut Which of the four arrangements is best for tightening a bolt? ABCD
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. 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. r lever arm points out from the pivot
Perpendicular Component Only the perpendicular component of the force can affect the tangential acceleration. For an angle ( ) between the force (F) and lever arm (r), the perpendicular component is Fsin . angle between lever arm and force
Moment of Force The force exerted on the lever arm is the moment of force. This is called torque ( ).
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: r ° °
Torque Wrench Consider the product rFsin . next rF(0.7)2rF = (1.4)rF (0.87)rF(3r/2)(F/2) = (3/4)rF