This document discusses different types of energy and forces. It defines work as being done by a force when a body is displaced through a distance in the direction of the applied force. Kinetic energy is the energy possessed by a body due to its motion, while potential energy is the energy possessed by a body due to its position or configuration. Conservative forces do work that depends only on the initial and final positions of a body, not the path taken, like gravity. Non-conservative forces do work that depends on the path, like friction. The work-energy theorem states that work done by net forces equals the change in kinetic energy of a body. Elastic collisions conserve kinetic energy and momentum, while inelastic collisions do not conserve all

1. Work is said to be done by a force when the body is
displaced actually through some distance in the direction
of the applied force.
Work

2. Work

3. Work done by a coolie

4. ENERGY
Energy of a body is defined as the capacity or ability of
the body to do the work.
KINETIC ENERGY
The kinetic energy of a body is the energy possessed by
the body by virtue of its motion.

5. KINETIC ENERGY

6. POTENTIAL ENERGY
The potential energy of a body is defined as the energy
possessed by the body by virtue of its position or
configuration in some field.
Potential Energy of a spring
Potential energy of a spring is the energy associated with
the state of compression or expansion of an elastic spring.
M
K

7. Conservative force
A force is said to be conservative if work
done by or against the force in moving a
body depends only on the initial and
final positions of the body, and not on
the nature of path followed between the
initial and the final positions.
For example, gravitational force is a
conservative force.

8. A force is said to be non-conservative, if
work done by or against the force in
moving a body from one position to
another, depends on the path followed
between these two positions.
For example, frictional forces are non-
conservative forces.
Non-conservative Forces

9. WORK -ENERGY THEOREM
According to this principle, work done by net force in
displacing a body is equal to change in kinetic energy of
the body.
Consider a body of mass m moving with velocity u.Let a
force F be applied on the body, so that it accelerated with an
acceleration a .

10. Relation Between K.E and
Linear Momentum

11. Conservation of Mechanical energy of a free
Falling body
Consider a body of mass m
initially at rest at point
A.The Point A is at a height
h above the ground.

12. COLLISION
A Collision is said to take place when either two bodies physically collide
against each other or when the path of one body is changed by the
influence of the other body.
(a)Elastic collision : A collision in which there is absolutely no loss of
kinetic energy is called an elastic collision. The basic characteristics of
an elastic collision are :
(i) The linear momentum is conserved,
(ii) Total energy of the system is conserved,
(iii) The kinetic energy is conserved.
(iv) The forces involved during elastic collisions must be
conservative forces.

13. (b) Inelastic collision : A collision in which there occurs some
loss of kinetic energy is called an inelastic collision.
The basic characteristics of an inelastic collision are :
(i) The linear momentum is conserved.
(ii) Total energy is conserved.
(iii Kinetic energy is NOT conserved. Obviously, a part of
kinetic energy is converted into some other form of energy
e.g., heat energy, sound energy etc.
(iv) some or all the forces involved in an inelastic collision
may be non-conservative in nature.

14. ELASTIC COLLISION (1-D)
Suppose two balls A and B of masses m and m are moving
initially along the same straight line with velocities u and
u respectively,
1
1
2
2

15. IN-ELASTIC COLLISION (1-D)
Suppose two balls A and B of masses m and m are moving
initially along the same straight line with velocities u and
u =0 ,
1
1
2
2

16. ELASTIC COLLISION (2-D)/OBLIQUE COLLISION