Torque and Tangential Force

Torque is a combination of force and distance that may be defined as twisting effort. This quantity is used in the analysis of rotating devices. In Fig. 1-5 a tangential force of F newtons applied to the free end of the crank having an arm of r m produces a torque of

T = rF newton meters

[1-24]

Figure 1-5. Force applied to a crank

The amount of energy put into the crank in rotating it through an infinitesimal angle of dθ radians is, from Eq. 1-1

[1-25]

The power associated with torque is

Where ω is the angular velocity in radians per sec. Hence, if n is the speed in rpm, the angular velocity is expressed by

[1-26]