This assignment report summarizes key concepts of force and laws of motion. It describes balanced and unbalanced forces, and how unbalanced forces can change a body's motion by starting, stopping, or changing the speed or direction of a moving body. The report discusses Galileo's experiment that uniform motion requires no force, and introduces Galileo's law of inertia stating an unaccelerated body will remain at rest or in straight line motion. It also defines inertia and introduces Newton's first, second, and third laws of motion, and the law of conservation of momentum.

1. ASSIGNMENT REPORT NO-1
TOPIC: FORCE & LAWS OF MOTION
GUIDED BY : SIR UDAY PAL(PGT)
Class:IX Sec:B Roll No:28

2. FORCE:
Force is an external agency which
can change the state of rest or
motion of configuration of a body.
Force are of two types:
 Balanced force
 Unbalanced force

3. Balanced force:
 When a number of forces acting
simultaneous on a body do not
bring about any change in its state
of rest or of uniform motion in a
straight line ,then it is balanced
force.

4. Unbalanced force:
 When a number of forces acting
simultaneously on a body bring
about a change in state of rest or
uniform motion in a straight line
,then it is known as unbalanced
force.

5. Balanced force:

6. Unbalanced force:

7. Effects of force:
 Force can bring a stationary body
in motion.
 Can stop a moving body.
 Can change the direction of a
moving body.
 Can change the speed of a moving
body.

8. Effects of force:

9. Galileo’s Experiment:
 According to Galileo,a uniform
motion in a straight line did not
require any force to maintain it.
 So if a body is in motion,it will
continue to move with the same
speed & along the same straight
line if it is left to itself & no
external influence acts on it.

10. Galileo’s law of
Inertia:
 When no unbalanced force is
exerted on a body ,it stays at rest
or moves in a straight line with
constant speed ,i.e. it will remain
unaccelerated.

11. 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.
 Mass is the measure of inertia.

13. First law of motion:

14. Second law of motion:

15. Third law of motion:

17. Conservation of
momentum:
 Sum of momenta of two objects
before collision is equal to sum of
momenta after the collision
provided there is no provided
unbalanced force acting on them.
 This is known as Law of
Conservation of Momentum.