Force and motion

1. FORCE AND MOTION
Definition:
Force is defined as:
“The pushing or pulling of an object is termed as force. It acts on an object. Force can be
contract force or long range force.”
Measurement:
It can be measured by spring scale.
Units:
Unit of force is newton.
Quantity:
Force is a vector quantity. That is it has a direction.
Examples:
Gravitational force, Pushing force, Pulling force.
Definition:
Motion can be defined as:
“The change in position of an object with respect to time. Change of position continuously
with respect to stationary environment”
Examples:
Running car on road, Walking on earth etc.
Types of Motion:
There are three types of motion:
Translation Motion:
When a body moves along a straight line its motion is termed as translation motion.
Example:
A car moving on a highway.
Rotational Motion:
When a body rotates along an axis then its motion is known as rotational motion.
Example:
Earth spins around its own axis.

2. Vibratory Motion:
The to and fro motion of an object is termed as vibratory motion.
Example:
Back and forth motion of simple pendulum.
Uniform Motion:
If a body travels equal distance in equal intervals of time then motion of this body is known
as uniform motion.
Example:
A car running at constant speed.
Non-Uniform Motion:
If a body do not covers equal distance in equal intervals of time then the motion of this body
is known as non-uniform motion.
Example:
Drop of ball from a roof
Relation among Force, Mass and Motion:
Sr.n
o.
Quantit
y
Definition Example Relation
1. Force The pushing or pulling of
an object is termed as
force.
Gravitational force. F=m/a
m is for mass
F is for force
A is for
acceleration.
2. Motion The change in position of
an object with respect to
time. Change of position
continuously with respect
to stationary environment.
Motion of car, walk on
earth.
Force is required
for an object to
move of a certain
mass it is the
relationship of
motion with force
and mass.
3. Mass A body of coherent matter,
usually of indefinite shape
and often of
considerable size
a mass of dough.
Car, Boy, Rock m=F/a
m is for mass
F is for force
A is for
acceleration.
Linear motion:
Motion of a body along a straight line or path is known as linear motion.

3. Quantity:
It is a vector quantity i.e it has a direction.
Example:
Motion of car on highway.
Graphical Representation:
Non- linear motion:
The motion of object at any angle it is known as non-linear motion. It is also known as
projectile motion.
Quantity:
It is a vector quantity i.e. it has a direction.
Example:
Movement of electron in two parallel and oppositely charged plates.
Graphical Representation:

4. Constant Motion:
It refers to any type of motion when either the distance traveled by the object is the same for
each second, or the speed of the object changes by the same amount each second.
Example:
Curst of earth, Car moving with constant speed.
Graphical representation:
Accelerated Motion:
It defined as the rate at which an object changes its velocity. An object is accelerating if it is
changing its velocity.
Quantity:
It is a vector quantity i.e. it has a direction.
Example:
A freely falling body, Planet around sun, Electron around sun.
Graphical representation:

5. LAW’S OF NEWTON
Introduction:
Sir Isaac Newton (1642-1727), an English physicist and mathematician, is one of the most
brilliant scientists in history. Before the age of 30, he formulated the basic laws of mechanics,
discovered the universal law of gravitation, and invented calculus! In 1665, shortly after
getting a bachelor’s degree at Cambridge, Newton was forced to return to his home because
of the Great Plague. During the next 18 months he formulated most of his scientific
discoveries: including, the development of his three Laws of motion, the Law of gravitation,
the invention of the calculus, the dispersion of light, the building of a reflecting telescope,
and so on. That short period was probably the most creative period in the history of man ...
and it will never be repeated!
Three Laws of Motion:
There are three laws of motion:
 Newton’s 1st
law of motion
 Newton’s 2nd
law of motion
 Newton’s 3rd
law of motion
1st
Law of motion:
Law of inertia:
Definition:
“An object at rest tends to stay at rest and an object in motion tends to stay in motion unless
acted upon by an unbalanced force.”
Balanced Force:
Equal forces in opposite directions produce no motion.
Unbalanced Force:
Unequal opposing forces produce an unbalanced force causing motion.
Friction:
A book sliding across a table slows down and stops because of the force of friction.
Gravity:
If you throw a ball upwards it will eventually slow down and fall because of the force of
gravity.
Mass:
• MASS is the measure of the amount of matter in an object.
• It is measured in Kilograms.

6. Inertia:
• Inertia is a property of an object that describes how much it will resist change to the
motion of the object.
• More mass means more inertia.
Types of Friction:
• There are four main types of friction:
– Sliding friction: ice skating
– Rolling friction: bowling
– Fluid friction (air or liquid): air or water resistance
– Static friction: initial friction when moving an object
Example:
 A book sliding across a table slows down and stops because of the force of
friction.
 If you throw a ball upwards it will eventually slow down and fall because of the
force of gravity.
2nd
Law of Newton:
“Change in motion depends on the mass of the object & the amount of force applied.”
Formula:
F=ma
F is for Force.
m is for Mass.

7. a is for Acceleration.
Explanation:
Force and acceleration are proportional to each other the amount of force is equal to
The amount of acceleration. The greater the force exerted on an object, the more it will
Accelerate. For example, the harder you kick a ball, the farther and faster it will travel.
The opposite is true of mass. The more mass an object has, the less it will accelerate. If you
Kick a tennis ball and a bowling ball with the same amount of force, the heavy bowling ball
is going to move slower and go a shorter distance than the tennis ball. A heavier object
Requires more force to set it in motion.
Example:
 Glacier of a mountain.
 Bullet of Gun.
3rd
Law of Motion:
Definition:
“For every action there is an equal and opposite reaction.”
Force Occurs in Pair:
 The astronauts working on the space station have a serious problem when they need to
move around in space: There is nothing to push on.
 One solution is to throw something opposite the direction you want to move.
 The two forces in a pair are called action and reaction.
 Anytime you have one, you also have the other.
 If you know the strength of one you also know the strength of the other since both
forces are always equal.

8.  Newton’s third law states that for every action force there has to be a reaction force
that is equal in strength and opposite in direction.
 Action and reaction forces act on different objects, not on the same object.
 Newton’s third law states that for every action force there has to be a reaction force
that is equal in strength and opposite in direction.
 Action and reaction forces act on different objects, not on the same object.
 The forces cannot cancel because they act on different objects.
Examples:
 Book placed on table.
 Walk on earth.