In mechanics, a couple refers to two parallel forces that are equal in magnitude, opposite in sense and do not share a line of action. A better term is force couple or pure moment. Its effect is to create rotation without translation, or more generally without any acceleration of the center of mass. http://bit.ly/2PIOIQM

1. Prepared By Atheena
Pandian
Force Couple

2. Scope of the
Guidelines
Waht is Force Couple?
Example
Unit
Application
1.
2.
3.
4.
KEY
CONCEPTS

3. A couple refers to two parallel forces that are equal in
magnitude, opposite in sense and do not share a line of
action.
WHAT IS
FORCE
COUPLE?

4. A better term is force
couple or pure moment.
Its effect is to
create rotation without t
ranslation, or more
generally without any
acceleration of
the centre of mass.
BIOMECHANICS
Couple (Mechanics)

5. SIMPLE
COUPLE
THE SIMPLEST KIND OF COUPLE
CONSISTS OF TWO EQUAL AND
OPPOSITE FORCES WHOSE LINES OF
ACTION DO NOT COINCIDE. THIS IS
CALLED A "SIMPLE COUPLE"

6. Forces which are not
concurrent and their lines of
action are not the same and
parallel to each other then the
forces are called parallel
forces.
Example: Children sitting on a
see-saw. Their weights are the
example of parallel forces. If
there are two forces which are
equal and opposite they form a
couple.
EXAMPLE

7. The moment (or torque) of
a couple is calculated by multiplying
the size of one of the force (F) by the
perpendicular distance between the
two forces (s).
How do you find the force
of a couple?

8. Newton Meter
S.I UNIT OF COUPLE
FORCE

9. Couple Force does not
produce any translation,
only rotation. The resultant force of a
couple is zero. BUT,
the resultant of a couple is
not zero; it is a pure
moment.

10. The magnitude of
the couple is
given by
Here,
F are the two forces
and
d is the perpendicular
distance between the forces
or is the moment arm.

11. Is Torque and
Couple same thing?
In engineering mechanics, torque is the
resultant moment of
a couple.
In general physics, it represents the
moment of a force.

12. APPLICATIONS
The forces exerted by one's hand on a screw-driver
The forces exerted by the tip of a screwdriver on the
head of a screw
Drag forces acting on a spinning propeller
Forces on an electric dipole in a uniform electric field.
The reaction control system on a spacecraft.Force
exerted by hands on steering wheel.
Couples are very important in mechanical
engineering and the physical sciences. A few examples
are:
1.
2.
3.
4.
5.

13. Thank You