This PPT prepared by student-Teacher from Thiagarajar College of Preceptors for Demo Class

1. S. MAHESWARI
1122119BD077
PHYSICAL SCIENCE

2.  Energy →force →function
 Work is done

3.  When force act on a body in such a way that body covers
some displacement, it is called work.
 Work is defined as a product of force(F) and
displacement(d).
 W=Fxd
 Work can be defined transfer of energy.
 Work is scalar quantity.
 SI unit of work is Joule ( J ).
 If force make an angle with direction of motion, then for
finding work done ,the component of force will be taken,
which act in the direction of motion ( F cosӨ).
 W = F cosө x d

5.  (a) when direction of force and displacement is same the
work done is positive.
 (b) when direction of force and displacement is opposite the
work done is negative.
 (c) when force and displacement are mutually perpendicular to
each other the work done is zero.

6.  Man does positive work lifting box
 Man does negative work lowering box.
 Gravity does positive work when box lowers.
 Gravity does negative work when box raised.

9.  Capability of doing work is called energy.
 In SI unit of energy is measured in Joule ( J ).
 Energy is scalar quantity.

10.  There are two basic kinds of energy,
kinetic energy
potential energy

11.  Definition:
energy produced produced by a object due to its
motion it called as kinetic energy (K.E.).
Examples ,
bullet fired from a gun and water flowing from dam
having kinetic energy.

12.  The work done by the constant force (F) for a displacement (s)
in the same direction is ,
 W=F.s --------------- (i)
 The constant force is given by the equation
 F=ma --------------- (ii)
 The third equation of motion is,
v2 = u2 +2as ------------ (iii)
In this case initial velocity ‘v’ and final velocity is ‘0’
i.e. V2 = 0+2as
s= v2/2a
Eqn. (ii) and (iii) in eqn. (i),
W= ma.v2/2a
K.E = ½ mv2

14.  Definition : capacity to perform work bye a body due to
its position or state or condition is termed potential
energy (P.E)
 Examples : Bullet loaded in a gun and water stored in a
dam have potential energy.
 The P.E possessed by a body in a gravitational fields is
gravitational P.E.

15.  W = F x d
 But F= mg for gravitational force act on object and d=
h for height
 W = mgh
 i.e. W(work) = P.E.
 P.E = mgh
 Where,
 g- acceleration due to gravity
 m- mass and h- height

17.  Definition : It is stored as a result of deformation of an
elastic object, such as stretching spring.

18.  Explanation : The force that is applied on object is
stored as its elastic potential energy, which helps the
object to restore its initial position.
 According to Hooke’s law F=kx
 Average force required for displacement (x) is F/2
 Hence work done for displacement is,
 W(work) = F/2× x (i.e. F=kx)
 EP= W = ½ kx2

19.  In unit time work performed is termed power.
 Power is a measure of how fast or slow a work is done.
 Power is defined as the rate of work done or energy
delivered.
 P=W/t. ( P- Power, W- Work and t- Time)
 Unit of power is watt (J/s).
 Power is scalar quantity.
 Other common unit of power is horse power (hp).
 1hp=746 watt