Torque…

DEFINITION OF TORQUE

Torque = = F l = (Magnitude of the force)×(Lever arm)

 

SI Unit of Torque: newton · meter (N · m)

Direction: The torque is positive when the force tends to produce a counterclockwise rotation about the axis, and negative when the force tends to produce a clockwise rotation.

There is a couple of ways of visualizing torque

The units for torque are usually Nm (not a joule) or lb.ft (pound feet).

Torque can be calculated using a perpendicular component of force or a perpendicular moment arm.

What’s wrong with this picture?

You are installing a new spark plug in your car, and the manual specifies that it be tightened to a torque of 37 N ·

m. Using the data in the drawing, determine the magnitude F of the force that you must exert on the

wrench.

F∙sin(50)∙0.28 = 37F = 172.5 N

Torques have a direction

In both cases, less force is required to produce rotation when the force is farther from the axis of

rotation

If a 1.23-N*m torque is required to pull a given weed, what force does the weed exert on the tool?

A claw hammer is being used to pull a nail out of a horizontal board. If the force is F=150 N is applied horizontally, find the force exerted

by the hammer claws on the nail and the force exerted by the surface on the point of contact.

If all five horizontal forces on this meter stick stick have the same magnitude, how do the

torques compare.