N1 Engineering Science|The Easy Way! 37 Tis turning effect is known as the moment of the force, or simply as a moment or torque. D


When the moment is in the direction shown, it is a clockwise moment (CWM) and when it is in the opposite direction, it is referred to as an anticlockwise moment (ACWM).


Definition 2.12 Moment of a force Te moment of a force is the turning effect of a force about a point.


Tis moment of a force is the product of the force and the perpendicular (or effective) distance from the turning point to the line of action of that force, i.e.


Moment = F × s Nm .......................................................................................... (2.6)


where Moment = turningmoment in Nm F = force in N s = perpendicular distance inmetres


2.9 Levers (1 force)


A lever is a rigid bar or other similar structure. When it is used to produce a turning moment at a point, such as the spanner already discussed, the turning moment is usually referred to as a torque (T).


Te perpendicular distance from the line of action of the force to the turning point, in this case, would be the radius of the arc or circle formed when the force moves or tends to move about the turning point. Tus:


T = F × r Nm ........................................................................................................ (2.7)


where T = torque in Nm F = force in N r = radius inm


Example 2.11


Determine the torque exerted on the nut, shown in the figure below, if the spanner has an effective length of 25 cm and the applied force is 30 N.


Solution:


Effective length “r” d = 0,25 m


T = F × r = 30 × 0,25 = 7,5 Nm


30 N r = 0,25 m = • 30 N


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