notes on 9th physics by asif rasheed

7/28/2019 Notes on 9th Physics by Asif Rasheed

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Ideal Science Academy

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Asif Rasheed BS (HONS) 0344 78 46 394 Page

Unit No 1

(1) Define Physics? (2) Ans: The branch of science which deals with the study of matter and energy and their mutual relationship

is called Physics.

(2) Write names of the branches of Physics?

Ans: (1) Mechanics (2) Heat & Thermodynamics (3) Sound (4) Light

(5) Electromagnetism (6) Atomic and Molecular Physics (7) Nuclear Physics (8) Plasma Physics (9) SolidPhysics

Which scientist invented a toy working on steam? Ans:

The famous scientist of Alexandria Hero invented the toy working on steam. (3) Define Plasma?

Ans: The state of matter at a very high temperature comprising the ions and electrons is called plasma.

(4) Name the branches of physics overlapping the other branches of science?

Ans: (1) Astrophysics (2) Geophysics (3) Biophysics

(7) Differentiate between observation and experiment?

Ans: To collect facts about the natural phenomena is called observation.

While Experiment is the organized process which is performed to test the truth of hypothesis.

(10) What is the best replacement of coal for the production of energy?

Ans: Solar energy and the atomic energy are two best replacements of coal for the production of energy.

(11) How much energy could be produced from Uranium?

Ans: Energy obtained by the breaking up of one kilogram of Uranium is equal to the energy obtained from the burning of 3 million kg of coal.

(12) In which state most of our universe exists?

Ans: Most of our universe is in the state of plasma.

(13) What is the work of Nichole Oresme in Physics?


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Asif Rasheed BS (HONS) 0344 78 46 394 Page 2

Ans: He studied in the change in velocity with the help of geometry.

(14) Who studied the freely falling bodies?

Ans: Galileo studied the freely falling bodies

15)Explain the theory of mass and energy? Ans:

In 20 th century Einstein told that the mass and energy are, in fact, forms of each othe r.(16)What was the major work of Dr. Abdus Salam? Ans:

in 1979 Dr. Abdus Salam gave the theory of unification in which he explained that weak nuclear force andelectromagnetic force are of same form.

MEASUREMENTS

Why a standard unit is need to measure a quantity correctly.Ans:

Various units have been in use in different times in different parts of the world. The fastmeans of communication systems have changed the world into a global village. Due to thisreason an international system of units for mutual business became essential.The eleventh general conference of weights and measures recommended that all the countries of world should adopted a system of same kind of standard units, consisting of seven base unitsknown as international system of units (SI) and derived units.

Q: What is meant by base and derived units? Give three examples of derived units andexplain how they are derived from base units. Ans:

Base Units:The units of base quantities are called base units.

Examples:

Kilogram (kg), meter (m), second (s), Ampere (A)

Derived Units:The units of derived quantities which are derived from base units are called

derived units.Examples:


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Asif Rasheed BS (HONS) 0344 78 46 394 Page

Unit of Area: m 2.Unit of Volume: m 3 Unit of Density: Kg m -3 Unit of speed: meter per second (ms -1),Unit of weight: NewtonUnit of force: Newton,Unit of Pressure: Pascal

Q : How they are derived from base units: These units are obtained by multiplication, division or both of base un its.Unit of Area: length x breadthUnit of length x unit of breadthMeter x meter

m x m: m2

Unit of Volume: length x breadth x heightUnit of length x unit of breadth x unit of heightMeter x meter x meter m x m x m: m3

Unit of Density: MassVolumeUnit of massUnit of volume

Q: What is the number of base units in System International (SI)? Ans.

There are seven base units which are given below Number Physical Quantity Unit Symbol1. Length Meter (m

2. Mass Kilogram(kg3. Time Seconds (s4. Electric current Ampere( A5. Temperature Kelvin( K 6. Intensity of light Candela(cd7. Amount of substance(Mole mol


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Q: Where multiples and sub-multiples of units are used? Describe some standardprefaces which are internationally used.

Ans. Multiples and sub-multiples of units are used to make very large and very smallmathematical calculations easier. The multiples and sub-multiples are obtained by multiplyingor dividing with ten or power of tens.

The terms used internationally for the multiples and sub-multiples for different units are called prefixes.

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Q: What is the use of vernier calipers? What is meant by its vernier constant? Ans.

A vernier calliper can be used to measure lengths accurately up to one tenth of a millimeter.Least Count/Vernier ConstantThe minimum length which can be measured accurately with the help of vernier scale or vernier calipers is called least count.Least count of vernier calliper is 1/10 mm or 0.1 cm which is also called vernier constant.

Q: Explain the statement A micrometer screw gauge measures more accurately than avernier caliper? Ans .

Least Count : The minimum length which can be measured accurately is calledleast count of any measuring device.

The least count of micrometer screw gauge is 0.01 mm and that of Vernier calliper is 0.1. mm.So a micrometer screw gauge measures more accurately than a vernier calliper.

Unit # 2 Kinematics

Define Mechanics and its types.The branch of physics, which deals with the study of motion of bodies, is called Mechanics. It has two types:


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I) Kinematics

ii) Dynamics

Define Types of Mechanics.Kinematics:

It is study of motion of bodies without reference of force and mass.

Dynamics:

It is study of motion of bodies with reference of force and mass.

Define RestIf a body does not change its position with respect to some observers then it i s said to be in the state of rest.

Define MotionIf a body is changing its position with respect of some observers then it is said to be in the state of motion.

Name the types of motiona. Translatory Motion

b. Linear motion

c. Circular motion

d. Random motion

e. Rotatory Motion

f. Vibratory Motion

What is the motion butterfly? Executed byFlight of butterfly is irregular motion. Therefore its motion is called random motion. What is type of motion of free falling bodies?

Freely falling bodies move downward in straight direction under the force of gravity. Therefore their motion

is called linear motion.

What is the type of motion of a man moving in circular track?His motion is circulatory motion.

Define DistanceThe path between two points is called distance. It is scalar quantity.

Define DisplacementThe shortest distance between two points is called displacement. It is a vector quantity.

What are Scalar and Vector Quantities?Scalars are those quantities which are described by a number with suitable unit without direction.

Vectors are those quantities which can be described by a number with suitable unit and with direction.

Define VelocityThe distance covered by a body in a unit time in a particular direction is called velocity.


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OR

The rate of change of displacement is called velocity. It is denoted by v. It is a vector quantity.

1. Positive Acceleration

If the velocity continuously increases then the acceleration will be positive.2. Negative acceleration

If the velocity continuously decreases then the acceleration will be negative.

Define Uniform SpeedIf a body covers an equal distance in equal interval of time in a particular direction, the body is said to be

uniform Velocity.

Define variable velocityIf a body does not cover an equal distance in equal interval of time

in a particular direction, the body is said to be in variable velocity.Define relative velocity

When two bodies are in motion then the velocity of one body

relative to other is called relative velocity.

Define Instantaneous velocityThe velocity of a body at any instance of time is called

instantaneous velocity.

Define Average velocityAverage velocity of a body can be obtained by dividing the total displacement with total time taken.

Vav = Displacement/Time = d/t

Can a body moving with certain velocity in the direction of East can have acceleration in the direction of West?

Ans:

Yes, if the velocity of the body decreases, then it will have acceleration in the opposite direction, that is,

in the direction of west.

Does speedometer of a car measures its velocity?It measures only speed but not velocity.

Define Acceleration.The rate of change of velocity is called acceleration. It is denoted by a. It is a vector quantity.

Define Uniform AccelerationIf velocity of a body is changing equally in equal intervals of times then its acceleration will be uniform.

Define Variable AccelerationIf velocity of a body is not changing equally in equal intervals of times then its acceleration will be variable.


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Define Average AccelerationThe average acceleration can be obtained by dividing total change in velocity with total time taken.

aav = Change in Velocity/Total Time

=(Vf Vi)t

Define Gravitational AccelerationThe acceleration of freely falling bodies is called gravitational acceleration. It is den oted by g. Its value

is 10 meter per second per second (10 ms -2)

2. A body is thrown vertically upward. What is gravitational acceleration?Ans :

It is 10 meter per second per second (10 ms -2)3. What is acceleration of a body moving with uniform velocity?

Ans :The acceleration will be 0.

4. What consideration should be kept in mind while using equation of motion for free falling bodies? Initial vel ocity should be taken as zero. Acceleration will be taken as (g) instead of (a)

Define SpeedThe distance covered in unit time is called speed.

Speed = Distance/Time

v = S/t

The unit of speed is meter per second (ms -1) or m/s

5. Can a body moving at a constant speed have acceleration?Yes, if it is moving in circular path, it can have acceleration.

6. A body is moving with uniform velocity, what will be its acceleration?Its acceleration will be zero.

7. A body is moving with a uniform speed. Will its velocity be uniform?Yes, if it moves in straight line and does not change its direction.

8. Can a body moving with a certain velocity in direction of East, have Acceleration in thedirection of West?Yes, if its velocity will decrease, it has acceleration in the direction of west.

9. Does speedometer a car measure its velocity? No, it only measures the speed.

10. Why a stone and a piece of paper when dropped from the same height, reach the ground at thesame time.Because both have same gravitational acceleration.

11. What type of change will occur in three equations of motion under the action of gravity?Acceleration (a) will be replaced with gravitational acceleration (g) in all equations.And distance (s) will be changed in to height (h).


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Three equations of motion are three equations of motion under the action of gravity are

Vf = V i + at V f =V i+gt

S = V i t + 1/2 at2

h=V it+1/2 gt2aS = V f 2 V i 2 2gh = V f 2 V i 2

Long Questions: -

Describe the different types of motion in detail?Motions of bodies are of three types:

i) Translatory Motion: -

A motion in which each particle of a body has exactly same motion is called Translatory Motion. It

may be of many kinds for examples: -

a. Linear Motion: If a body moves in straight line its motion is called linear motion.

e.g. motion of free falling bodies, a man walking on a straight path

b. Circular Motion: If a body moves in a circle its motion is called circular motion.

e.g. motion of stone attached to thread and whirled.

c. Random Motion: If a body moves in irregular manner its motion is called random

motion. e.g. motion of butterfly.ii) Rotatory Motion: -

Motion is said to Rotatory, when the object rotates on its own axis.

Examples: Rotatory motion of a planets on its axis, wheels of a vehicles, spinning top, ceiling fan etc .

iii) Vibratory Motion: -

When a body moves to and fro about a point and repeats its motion then its motion is called vibratory

motion. e.g. Motion of simple Pendulum, motion of tuning fork, A ruler. Place one inch of it on a desk,

and the other 11 off the desk. Flick the end off the desk and watch it vibrate.

Motion Graphs

For b ody moving at constant velocity:
http://physics.tutorvista.com/motion/motion-graphs.htmlhttp://physics.tutorvista.com/motion/motion-graphs.htmlhttp://physics.tutorvista.com/motion/motion-graphs.html


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The graph of straight line parallel to the X axis shows that the body is moving with constant velocity

a)

Derivation of Equation of Motion (Graphically)First Equation of Motion

Consider an object moving with a uniform velocity u in a straight line. Let it be, given a uniform acceleration at time, t = 0 when its initial

velocity is V i. As a result of the acceleration, its velocity increases to V f (final velocity) in time t and s is the distance covered by the

object in time t. The figure shows the velocity-time graph of the motion of the object.

Slope of the V f - t graph gives the acceleration of the moving object.

Thus, acceleration = slope = AB = BC/AC

Where BD=Vf, CD=Vi, AC= OD=t BC=BD-CD

(Average,acceleration(a av)= ChangeinVelocity/time)

Slope=AB= V f - Vi/ t


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a = V f - Vi/ t

Vf Vi = at

Vf = Vi + at ........................................................(1)

Second Equation of Motion

Let V i be the initial velocity of an object and 'a' the acceleration produced

in the body. The distance travelled s in time t is given by the area

enclosed by the velocity-time graph for the time interval 0 to t.

Distance travelled S = area of the trapezium ABDO

Total aera of OABD= area of rectangle ACDO + area of ABC

= OD x OA + (BC x AC)

Where, OA=V I, OD=t, BC=BD-CD, AC=t, BD=Vf, CD=Vi

= t x V i + (Vf - Vi ) x t

= Vi t + (Vf - Vi ) x t(vf = V i + at I eqn of motion; vf - vi = at)

S = V i t + 1/2 at x t

S = Vt + 1/2 at 2.

Third Equation of Motion Let 'u' be the initial velocity of an object and a be the acceleration produced in the body. The distance travelleds in timet is given by

the area enclosed by the v - t graph.

S= area of the trapezium OABD.

= 1/2 (OA + BD) x AC where OA=Vi, BD= Vf, AC=OD=t

= 1/2 (Vi + V f )t ....(1)

But we know that a =( V f - Vi )t


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Or t = (V f - Vi )a

Substituting the value of t in eq. (1) we get,

s = 1/2 (Vi + Vf )( Vf Vi)a = 1/2 (Vf + Vi)( Vf Vi)a

2as = (V f + V i) ( V f - Vi )

(Vf + V i)( Vf - Vi) = 2as [using the identity a2

- b2

= (a + b) (a - b)]

v2 - Vi 2 = 2as........... Third Equation of Motion

Acceleration Due To Gravity Or Free Falling Objects

Galileo was t he first scientist to observe that, neglecting the effect of air resistance, all bodies in free-fall close

to the Earths surface accelerate vertically downwards with the same acceleration: namely 9.8 m/s 2

ExampleIf a ball is thrown vertically upward, it rises to a particular height and then falls back to the ground. However

this is due to the attraction of the earth which pulls the object towards the ground

Characteristic Of Free Falling Bodies

1. When a body is thrown vertically upward, its velocity continuously decreases and become zero at a particular

height During this motion the value of acceleration is negative and V f is equal to zero

(a = -9.8m/s 2 , V f = 0).

2. When a body falls back to the ground , its velocity continuously increases and become maximum at a

particular height During this motion the value of acceleration is positive and Vi is equal to zero (a = 9.8m/s 2 , V

= 0).

3. Acceleration due to gravity is denoted by a and its value is 9.8m/s 2 .

4. Equation of motion for the free-falling bodies be written as,

V f = V i + gt

h = V i t + 1/2 gt 2

2gh = V f 2 V i

2


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Chapter # 3 Dynamics

1. FORCE

The Force is an agent which produces or tends to produce a motion in a body or it stops or tends to stop themotion of a body. In simple words we can also say that force is an agent which changes or tends to change the state

object.

UNIT

The unit of a Force in M.K.S System is Newton

2. MASS

The quantity of matter contained in a body is called mass. It is a scalar quantity.

FORMULA

F = ma

m = F/a

UNIT

The unit of mass in M.K.S System is Kilogram (kg).

3. WEIGHT

The force with which earth attracts other bodies towards its centre is called weight. It is a vector quantity.

FORMULA; W = mg

UNIT

The unit of weight in M.K.S System is Newton (N).

INERTIA

Definition

Inertia is the tendency of a body to resist a change in its state.

Examples

Cover a glass with a post card and place a coin on it. Now strike the post card swiftly with the nail of your

finger. If the stroke has been made correctly, the postcard will be thrown away and the coin will drop in theglass.


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If a moving bus stops suddenly, the passenger standing in it feels a jerk in the forward direction. As a result he

may fall. It is due to the fact that the lower part of the standing passengers comes to rest as the bus stops. But

the upper portion remains in motion due to inertia.

Difference between Mass and Weight

Mass

1. The quantity of matter present in a body is called mass.

2. The mass of a body remains constant everywhere and does not change by change in altitude.

3. It is a scalar quantity.

4. Mass can be determined by a physical balance.

Weight1. The force with which the earth attracts a body towards its centre is called the weight of the body.

2. The weight of a body is not constant. It is changed by altitude.

3. Weight is always directed towards the center of the earth. So it is a vector quantity.

4. Weight can be determined by only a spring balance.

MOMENTUM

The quantity or quality of motion is called momentum and it is denoted by P

MATHEMATICAL DEFINITION

It is the product of mass and velocity.

MATHEMATICAL REPRESENTATION

P = mV

where:

p is the momentum

m is the mass

v the velocity

LAW OF MOTIONS

Newton formulated three laws of motion in his book.

NEWTON FIRST LAW OF MOTIONS


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Newtons first law of motion is also known as the Law of Inertia.

STATEMENT

Every body continues its state of rest or uniform motion in a straight line until it is acted upon by an external o

unbalance force to change its state of rest or uniform motion.

EXPLANATION

This law consists of a two parts

(a) When body is at rest

(b) When body is moving with uniform velocity

(a). When a body is at rest

Newtons Law states that when a body is at rest, it continues its rest unless we apply a force on it. When we

apply a force, it changes its state of rest and starts moving along a straight line.(b) When body is moving with a uniform velocity

Newtons Law states that when a body is moving, it moves in a straight line with uniform velocity, but when we

apply an opposite force, it changes its state of motion and come to rest.

Examples

If a bus suddenly starts moving, the passengers standing in the bus will fall in the backward direction. It is due

to the reason that the lower part of the passengers which is in contract with the floor of the bus is carried

forward by the motion of the bus, but the upper part of the body remains at rest due to inertia and so the

passengers fall in backward direction.

If a bus suddenly stops moving, the passengers standing in the bus will fall in the forward direction. It is due to

the reason that the lower part of the passengers which is in contract with the floor of the bus is stopped with the

bus, but the upper part of the body remains moving due to inertia and so the passengers fall in forward direction.

SECOND LAW OF MOTION

STATEMENT

When a force acts on an object it produces an acceleration which is directly proportion to the amount of theforce and inversely proportional to the product of mass EXPLANATION

When we push a body with greater force then its velocity increases and change of velocity takes place in the directio

force.If we apply a certain force F on a mass m, then it moves with certain velocity in the direction of the force.


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If the force becomes twice then its velocity will also increase two times. In this way if we go on increasing the

fore there will be increase in velocity, which will increase the acceleration.

DERIVATION

According to the Newton`s Second law of motion when a force acts on an object it produces an accelerationwhich is directly proportion to the amount of the force.

a F

and inversely proportional to the product of mass

a 1/m

Combining both.

a F/m

A = constant F/m

a = k F/m

If the Value of constant K is 1

so,

a = F/m

or

F = ma

THIRD LAW OF MOTION

Statement:

To every action there is always an equal and opposite reaction

EXPLANATION

According to Newtons Law of Motion, we have:

F(action) = F(reaction)

The negative (-) sign indicates that the two forces are parallel but in the opposite direction. If we consider one

of the interacting objects as A and the other as B, then according to the third law of motion:

F(AB) = F(BA)F(AB) represents the force exerted on A and F(BA) is the force exerted on B.

Examples

We walk on the ground, we push the ground backward and as a reaction the ground pushes us forward.

Due to this reason we are able to move on the ground.


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If a book is placed on the table, it exerts some force on the table, which is equal to the weight of the book. The

table as a reaction pushes the book upward. This is the reason that the book is stationary on the table and it does

not fall down.

FRICTION

Definition

The force, which resists the motion of one surface on

another surface, is known as

friction.

Explanation

Suppose a wooden block is placed on a table and a spring balance is attached on it. If we apply a very small force o

F by pulling the spring gradually and increase it, we observe that the block does not move until the applied force h

critical value. If F is less then critical value, the block does not move. According to Newtons Third Law of moti on an oppos

force balance the force. This opposing force is known as the force of friction or friction.

CausesofFriction

If we see the surface of material bodies through microscope, we observe that they are not smooth. Even the

most polished surfaces are uneven. When one surface is placed over another, the elevations of one get

interlocked with the depression of the other. Thus they oppose relative motion. The opposition is known as

friction.

Factors on which Friction Depends

The force of friction depends upon the following factors:

1. Normal Reaction (R)

Force of friction is directly proportional to normal reaction (R), which act upon the body in upward direction

against the weight of the body sliding on the surface.


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2. Nature of Surfaces

Force of friction also depends upon the nature of the two surfaces. It is denoted as u and has constant values for

every surface. It is different for the two surfaces in contact.

Coefficient Of FrictionThe coefficient of friction is a number which represents the friction between two surfaces. Between two equal

surfaces, the coefficient of friction will be the same. The symbol usually used for the coefficient of friction is

Greek letter , where 0 1 .

The maximum frictional force (when a body is sliding) is equal to the coefficient of

F =friction the normal reaction force.

R

Where is the coefficient of friction and R is the normal reaction force.

This frictional force, F, will act parallel to the surfaces in contact and in a direction to oppose the motion that is

taking/ trying to take place.

Advantages of Friction

1. We could not walk without the friction between our shoes and the ground. As we try to step forward, we push

foot backward. Friction holds our shoe to the ground, allowing you to walk.

2. Writing with a pencil requires friction. We could not hold a pencil in our hand without friction.

3. A nail stays in wood due to friction

4. Nut and bold hold due to friction

DISADVANTAGES OF FRICTION

1. In any type of vehicle such as a car, boat or airplane excess friction means that extra fuel must be used to power the v

In other words,fuel or energy is wasted because of the friction.

2. The Law of Conservation of Energy states that the amount of energy remains constant. Thus, the energy that is lost

friction in trying to move an object is really turned to heat energy. The friction of parts rubbing together creates heat

3. Due to the friction a machine has less efficiency less than 100%.

4. Due to friction machine catch fire.


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Laws of Friction

Statement

The value of limiting friction increases proportionally with the increase in normal reaction. Hence, liming

friction F(s) is directly proportional to the normal reaction.

F(s) < R (Here < represents the sign of proportionality dont write it in the examination paper.)

=> Fs = R .. (i)

u = F(s)/R

u is the constant of proportionality, which depends upon the nature of the surfaces of the two surfaces in

contact. It is known as the coefficient of friction. It is only a number without any unit. We know that the normal

reaction is directly proportional to the weight of the block, therefore,

R = W = mgSubstituting the value of R in equation (i)

=> Fs = mg

Rolling Friction

When a body rolls over a surface, the force of friction is called rolling friction. Rolling friction is much less than

the sliding friction. This is because the surfaces in contact are very much less.

LONG QUESTIONSQuestion: Explain the Law of Conservation of Momentum?This law states that

When two or more bodies collide with one another the total momentum of the

system remains the same, provided no external force acts upon them.

Explanation: -The law of conservation of momentum is a fundamental law of nature, and it states that the total momentum of

an isolated system of objects (which has no interactions with external agents) is constant. One of the

consequences of this is that the of any centre of mass system of objects will always continue with the samevelocity unless acted on by a force outside the system.

Consider two balls of masses m 1 and m 2. They are initially moving with velocities u 1and u 2 in same direction on

a straight line. If u 1 > u 2, then the balls will collide. Let their velocities becomes v1 and v2 after collision.


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Total momentum of balls before collision = m 1u1 + m 2u2

Total momentum of balls after collision = m 1v1 + m 2v2

According to Law of conservation of momentum

Total Momentum before collision = Total Momentum after collisionm1u1 + m 2u2 = m 1v1 + m 2v2

Question: Define friction and describe the types of friction ?

Question: What is force of friction? How friction can be reduced?Friction: -The force, which resists the motion of one surface on another surface, is known as

friction.

Methods to reduce friction: -i) Sliding parts should be highly polished to reduce friction.

ii) Friction of liquids is less than solids. Therefore oil or grease is applied between the parts of machinery.

iii) Rolling friction is less then sliding friction. Therefore sliding friction should be converted to rolling friction

by using ball bearings.

iv) Front side of vehicles, aeroplanes and ships are shaped wedge like and pointed so that minimum friction isoffered by air.

Centripetal ForceDefinitionThe force that causes an object to move along a curve (or a curved path) is called centripetal force.


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Mathematical Expression

We know that the magnitude of centripetal acceleration of a body in a uniform circular motions is directly

proportional to the square of velocity and inversely proportional to the radius of the path Therefore,

a(c) v2

a(c) 1/r

Combining both the equations:

a(c) v2/r

From Newtons Second Law of Motion:

F = ma

=> F(c) = mv 2/r

Where,

Fc = Centripetal Force m = Mass of object

v = Velocity of object r = Radius of the curved path

Banking of the roads Factors on which Fc Depends :

Fc depends upon the following factors:

Increase in the mass will increases Fc.

It increases with the square of velocity.

It decreases with the increase in radius of the curved path.

When a car takes

Examples

The centripetal force required by natural planets to move constantly round a circle is provided by the

gravitational force of the sun.


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If a stone tied to a string is whirled in a circle, the required centripetal force is supplied to it by our hand. As a

reaction the stone exerts an equal force which is felt by our hand.

The pilot while turning his aero plane tilts one wing in the upward direction so that the air pressure may providethe required suitable Fc.

Centrifugal ForceDefinition

A force supposed to act outward on a body moving in a curve is known as centrifugal force.

Explanation

Centrifugal force is actually a reaction to the centripetal force. It is a well-known fact that Fc is directed towards

the centre of the circle, so the centrifugal force, which is a force of reaction, is directed away from the centre of

the circle or the curved path.

According to Newtons third law of motion action and reaction do not act on the same body, so the centrifugal force d

act on the body moving round a circle, but it acts on the body that provides Fc.

Examples

If a stone is tied to one end of a string and it is moved round a circle, then the force exerted on the string on

outward direction is called centrifugal force.

The aeroplane moving in a circle exerts force in a direction opposite to the pressure of air.

When a train rounds a curve, the centrifugal force is also exerted on the track.

Two long question learn from book,

a) Find acceleration and tention in string when objects move vertically? b) Find Tention and acceleration when one object moves vertically and other one horizontally?

notes on 9th physics by asif rasheed

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