Page 6 - LN
P. 6
W=Fdcosθ
o Now again consider the figure 1 where PQ is the actual displacement
but here you must note that PQcosθis the displacement of the block in
the direction of force which is along PR. So, we can say that PQcosθ is
the component of displacement PQ along PR.
o So, general equation of work done would be
Work=force × component of displacement along the direction of force
Work
In our daily life anything that makes us tired is known as work. For example,
reading, writing, painting, walking, etc. In physics work (W) is said to be done, when
a force (F) acts on the body and point of application of the force is displaced (s) in
the direction of force.
Work done = force x displacement or, W = F x s
(i) If the body is displaced in the same direction of force, Work done is positive
(ii) If the displacement is against a force, the work is done against the force. Work
done is negative
(iii) If the displacement is perpendicular to the direction of the force, work done is
zero.
Unit of work
Unit of work is joule (J).
One joule of work is said to be done when a force of 1 Newton acting on a body
displacing it by 1 m. Larger units of work are (i) kilo joules (1000 joule) (ii) mega joule
(10 lakh joule)
