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Torque Web Quest. Helpful Hints. Part I: Definition of Torque. Torque is defined as the tendency to produce a change in rotational motion. Examples:. Each of the 20-N forces has a different torque due to the direction of force. Direction of Force. 20 N. q. 20 N. q. 20 N.
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Torque Web Quest Helpful Hints
Part I: Definition of Torque Torque is defined as the tendency to produce a change in rotational motion. Examples:
Each of the 20-N forces has a different torque due to the direction of force. Direction of Force 20 N q 20 N q 20 N Magnitude of force The 40-N force produces twice the torque as does the 20-N force. Location of force The forces nearer the end of the wrench have greater torques. 20 N 40 N 20 N 20 N 20 N Torque is Determined by Three Factors: • The magnitude of the applied force. • The direction of the applied force. • The location of the applied force.
6 cm 40 N Units for Torque Torque is proportional to the magnitude of F and to the distance r from the axis. Thus, a tentative formula might be: t = Fr Units: Nm or lbft t = (40 N)(0.60 m) = 24.0 Nm, cw t = 24.0 Nm, cw
cw ccw Sign Convention for Torque By convention, counterclockwise torques are positive and clockwise torques are negative. Positive torque: Counter-clockwise, out of page Negative torque: clockwise, into page
Part II: Moments of Inertia • The moments of inertia for many shapes can found by using the following: • Ring or hollow cylinder: I= MR2 • Solid cylinder: I= (1/2)MR2 (use for part II in lab) • Hollow sphere: I= (2/3)MR2 • Solid sphere: I= (2/5)MR2
A rotating mass on a rod can be described with variables from linear or rotational motion. Rotational Inertia
Rotational Inertia • To put the equation into rotational motion variables, the force is replaced by the torque about the center of rotation. • The linear acceleration is replaced by the angular acceleration.
Linear and Angular Acceleration Angular acceleration (kg) a = a r Linear acceleration (m/sec2) Radius of motion (m)
If you apply a torque to a wheel, it will spin in the direction of the torque. The greater the torque, the greater the angular acceleration. Rotation and Newton's 2nd Law
Part III: Angular Momentum • Momentum resulting from an object moving in linear motion is called linear momentum. • Momentum resulting from the rotation (or spin) of an object is called angular momentum.
L = Iw Calculating angular momentum Angular momentum is calculated in a similar way to linear momentum, except the mass and velocity are replaced by the moment of inertia and angular velocity. Moment of inertia (kg m2) Angular momentum (kg m/sec2) Angular velocity (rad/sec)