2. “Force is an agent that tends to change the state of
a body”
“Force is an agent that tends to stop the motion of a
moving body or tends to move the body in rest”
OR
3. NEWTON’S LAWS OF MOTIONS
Any objects continue to move in a state of constant velocity unless
acted upon by an external net force or resultant force & vice versa.
Force is directly proportional to accelaration if mass remains
constant :
F ∝ a
F = ma
To every action there is equal and opposite reaction.
4. Types of Forces
A force that is exerted on a body by another body,
that may or may not change the state of a body.
Normal force can be defined as the support force
exerted upon an object that is in contact with
another stable object.
Friction is a surface force that opposes relative
motion of two solid surfaces. It increases with
roughness of a surface.
5. Tension is describes as the pulling force exerted by each end
of a string OR The force directed along stretched objects.
An elastic force acts to return an object to its natural length
or shape.
A force by which bodies are drawn or in any way tend,
towards a centre of the circular path along which they are
moving.
&
The opposite force of the centripetal force is centrifugal
force.
6. The force by which earth attracts a body towards its centre.
Newton's law of universal gravitation states that any two bodies in
the universe attract each other with a force that is directly
proportional to the product of their masses and inversely proportional
to the square of the distance between them.
F ∝ m1m2
F ∝ 1 / r2
F = G m1m2
r2
r
7. “The force between two charged particles”
The force between two charged particles is directly
proportional to product of their charges and inversely
proportional to the square of the distance between them.
F ∝ q1q2
F ∝ 1 / r2
8. “A force that is exerted on a body for a very short
interval of time.”
It is equal to product of force and the time that in which it
exerted:
I = F Δt
9. Impulse on an object is equal to the change in momentum of an
object:
I = Δp
And we know that:
I = F Δt
Comparing:
F Δt = Δp
Or F = Δp
Δt
“It means the force is equal to the rate of change of momentum”
10. Work done is the product of force & displacement of a
body:
W = F.d
Force exerted per unit area of a body:
P = F / A
Torque or moment of force is the tendency of a force to rotate an
object about an axis or turning effect of force:
T = r × F
11. Gears that are running most of the machine
parts.
Spring attached to reed.
Force exerted on yarn in drafting.
Stretch or tension in warp yarns and other
processes.
Static buildup due to friction.
12. • From lectures of sir mazhar jamil.
• https://www.google.com.pk/search?q=gravita
tional+force&espv=2&biw=1366&bih=667&so
urce=lnms&sa=X&ei=KMQ5VfnvHcTgaJLigKgE
&ved=0CAYQ_AUoAA&dpr=1
• http://en.wikipedia.org/wiki/Force