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11.2 Turning force
Why is it easier to
unscrew a nut with a
long wrench than with
a shorter one?
textbooks nis edu kz
Why does a seesaw
balance? What would
happen if the person
on the left moved
towards the pivot?
hinge spring
r door
⍺
d
108
Turning force
When an object turns or rotates because of a force, it changes its state
of static equilibrium. A force is applied and thus a turning movement
occurs. This is called torque, or turning force. A force applied to a rigid
body that can be rotated around some point, generates torque. Torque
(turning force) makes an object turn (rotate) around a point called the
pivot. In the image below, the pivot is the nut.
Torque – turning
force
An important point is that maximum turning force must be applied
perpendicular to the pivot. The distance from the pivot (d) is also called the
lever’s arm. A lever is any object that turns around a point due to a force.
The moment of force is calculated as follows:
moment of force = force x distance from the pivot
M = F ∙ d
where М = moment of force, F = force in N, d = distance from pivot,
in metres.
Unit of measurement of moment of force in SI = 1 N ∙ m
A lever is a simple device that rotates around a pivot,
which is a non-movable support. A heavy load can
be moved with a small force using the lever. A
wheelbarrow is a great example of a simple lever.
INV Why are door handles (even on wardrobe doors) not placed in the
centre? Explore how the force applied depends on the distance to the
pivot. Record your results systematically.