This is a power point presentation which is sure to enrich everyone's knowledge on Force and Laws of Motion.

1. FORCE AND LAWS OF MOTION
DONE BY CHRIS VINOD

2. FORCE
Force is the effort needed to push or pull or to change the shape of a
body. It is any interaction that, when unopposed, will change the
motion of an object. In other words, a force can cause an object with
mass to change its velocity i.e. to accelerate. A force has both
magnitude and direction, making it a vector quantity. It is measured
in the SI unit of Newtons and represented by the letter F.

3. EFFECTS OF FORCE
 Force can cause motion in a stationary body.
 Force can stop a moving body.
 Force can change the direction of motion of a body.
 Force can change the speed of a moving body.
 force can change the shape and size of a body.

4. BALANCED AND UNBALANCED FORCE
Balanced Force
When a number of forces acting simultaneously on a body do not bring
about any change in its state of rest or uniform motion in a straight line,
then the forces acting on the body are said to be balanced forces.
The net force will be zero in this case.
Eg: a boy holding school bag in his hand.

5. • Unbalanced force
When a number of forces acting on a body bring about a
change in its state of rest or uniform motion in a straight line,
then the forces acting on the body are said to be unbalanced
forces.
Thus to move an object, an unbalanced force is required.
eg:

6. NEWTON’S FIRST LAW OF MOTION
Every body continuous to be in its state of rest or of uniform
motion in a straight line unless it is compelled by some external
applied force to change that state.

7. INERTIA
The inherent property of a body by virtue of which it resists any
change in its state of rest or of uniform motion in a straight line
on its own is called inertia.

8. INERTIA OF REST
eg: A passenger in a bus fall backward when the bus starts
suddenly.
When the bus starts suddenly the lower part of the passenger’s
body starts moving forward with the bus. But the upper part of
the body tends to remain in the state of rest due to the inertia of
rest.

9. INERTIA OF MOTION
A passenger in a moving bus tends to lean forward when the bus
stops suddenly.
When the bus stops suddenly the lower part of the passengers
body comes to rest along with the bus. The upper part of the body
tends to remain in the state of motion

10. LINEAR MOMENTUM
The linear momentum of a body of mass m, travelling with a velocity
v is defined as the product of its mass and velocity.
P = mass * velocity
P =mv
SI unit of momentum = kg m/s

11. NUMERICAL
Calculate the momentum of a toy car weighing 200g moving with the
velocity of 5m/s.
Mass = 200g
200g = 0.2 kg
Velocity = 5m/s
p = mv
0.2 * 5 = 1 kg m/s

12. NEWTON’S SECOND LAW OF MOTION
The rate of change of momentum of a body ids directly
proportional to the applied unbalanced force in the direction
of force.

13. MATHEMATICAL FORMULATION OF SECOND LAW OF MOTION.
Consider a body of mass ‘m’, having an initial velocity ‘u’. A force ‘F’
act on this body for time ‘t’. Let the final velocity be ‘v’.
Initial momentum of the body = mu
Final momentum of the body = mv
Change in momentum of the body = m(v – u)
According to the second law of motion,
F = m(v – u)/ t
F = Km(v – u)/t [ { v – u }/t = a ]
F = Kma [ K = 1 ]
F = ma

14. NUMERICAL
What is the acceleration produced by a force of 12N exerted on an object
of mass 3kg.
Force of the object = 12N
Mass = 3 kg
Acceleration = ?
F = ma
A = f/m
= 4 m/s

15. NEWTON’S 3RD LAW OF MOTION
For every action there is an equal or opposite
reaction.