Understanding Torque: Concept, Calculation, and Applications, Slides of Physics

Download Understanding Torque: Concept, Calculation, and Applications and more Slides Physics in PDF only on Docsity! Torque Docsity.com Tough Nut  Which of the four arrangements is best for tightening a bolt? F A B C D 2/F F F2 r r 2/3r r 45 60 Docsity.com 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. r̂  angle between lever arm and force F  ta  Docsity.com Moment of Force  The force exerted on the lever arm is the moment of force.  This is called torque ().  sinrF Docsity.com 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: F r ° ° N230 )113sin()m45.0( mN95 sin sin      F r F rF    Docsity.com Conservation of Energy  The net work done by forces on an object equals the change in kinetic energy.  The net work done by torques on an object equals the change in rotational kinetic energy. 2 2 12 2 1)( ifrot IIKW   Docsity.com Rotational Power  As with translational motion, power is the rate of work done.  The earth is slowing due to the tides. • About 28 s / century • 1 part in 108  The kinetic energy is changing.  The power dissipation is large: • About 7 billion hp next t II P tt WP if           2 2 12 2 1   Docsity.com