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.