Work
Definition:
work is done when a force acts ona body
and displace it int the direction of force
and displace it int the direction of force
Formula:work is the product of force and displacement in the direction of
force
force
W= F S
Unit:
Joule or Nm or kg m2 s-2
Joule or Nm or kg m2 s-2
quantity: work Is a Scalar quantity
work
done when force and displacement are not along same line :
done when force and displacement are not along same line :
Sometimes force and displacement do not have the
same direction
such as shown in figure
same direction
such as shown in figure
Here the force F
is
making an angle
θ with
the surface on which
Work done by a force inclined with the
displacement.
the body
is moved.
is
making an angle
θ with
the surface on which
Work done by a force inclined with the
displacement.
the body
is moved.
Resolving F into its perpendicular components Fx and Fy as
Fx= F
Cos θ
Cos θ
Fy= F Sin θ
when force and displacement are not along the
same line then horizontal component of the force is taken
same line then horizontal component of the force is taken
Fx= F
Cos θ
Cos θ
W=Fx S
W=F Cos θ S
W=F S Cos θ
W=F S Cos θ
Dependence
of work
of work
work depends upon the following factors
•force
•Displacement
•angle
between force and displacement
between force and displacement
Unit
of work
of work
SI unit of work is joule (J). It is
defined as
defined as
Joule
The amount of work is one joule when a
force of one newton displaces a body through one metre in the direction of force.
force of one newton displaces a body through one metre in the direction of force.
Thus 1 J = 1 N x 1m
Joule is a small unit of work. Its bigger
units are:
units are:
1 kilo joule (1kJ) = 1000 J = 103 J
1mega joule (1MJ) =1000 000 J =10 6J
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