VIEWS: 10 PAGES: 9 POSTED ON: 3/23/2011
Ch. 11 Rotational Mechanics Torque TORQUE Produced when a force is applied with leverage. Force produces acceleration. Torque produces rotation. TORQUE Torque = Force X Lever Arm Force must be perpendicular to lever arm. Torque is increased by – increasing force – increasing length of lever arm A torque is used when… Opening a door Turning on a faucet Tightening a bolt with a wrench Using a screwdriver Using a lever Balancing Torques Torques are balanced when clockwise torque = counter-clockwise torque. A meter stick is balanced at its center and a 20 N block is hung at the 80 cm mark. Another block is hung at the 10 cm mark. What is the weight of the 2nd block? Toppling and Tumbling When the CG is not over the area of support, a torque is produced - toppling. When a force is applied at the CG, no torque is produced. When a force is applied off center, a torque is produced - tumbling – Object will rotate about its CG. ROTATIONAL INERTIA An object rotating about an axis tends to keep rotating about that axis. Rotational Inertia - the resistance of an object to changes in its rotational motion. It takes a force to change linear state of motion. It takes a torque to change rotational state of motion. ROTATIONAL INERTIA Depends on mass and the distribution of the mass. – The greater the dist. between the bulk of the mass of an object and the axis about which rotation takes place, the greater the rotational inertia. Long objects are harder to rotate than shorter objects ROTATIONAL INERTIA Not necessarily a fixed quantity Can be changed by changing distribution of mass – choke up on a bat – bend legs – holding an object The farther the mass from the axis, the greater the rotational inertia.
Pages to are hidden for
"Ch Rotational Mechanics"Please download to view full document