9th Physics KPK Course

Chapter No :1

Quantities and Measurements

Important Terminologies and Definitions:

· Science :

The word science comes from the Latin "scientia," meaning knowledge.

The branch of Knowledge in which The intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.

Simple Definition of science. : Knowledge about or study of the natural world based on facts learned through experiments and observation. : A particular area of scientific study (such as biology, physics, or chemistry): a particular branch of science.

· Matter:

Matter is the any thing around us that have volume(occupy space ) weight and can be since by our five since There are five known phases, or states, of matter:

· Solids: In a solid, particles are packed tightly together so they are unable to move about very much.

· Liquids: In the liquid phase, the particles of a substance have more kinetic energy than those in a solid. The liquid particles are not held in a regular arrangement, but are still very close to each other

· Gases: Gas particles have a great deal of space between them and have high kinetic energy.

· Plasma: Plasma consists of highly charged particles with extremely high kinetic energy

· Bose-Einstein condensates; A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero (that is, very near 0 K or −273.16 °C).

· Energy :

The ability of a body to do work is called energy,

The prosperity of a body to by which it perform some work is called Energy.

· Atom :

Atom is the basic unit structure of a matter which can exist independently in nature

· Subatomic particles :

Name	Charge	Mass	Composition
Electron	Negative , 1.602 x 10^-19 coulombs (C)	9.10938356 × 10^-31 kilograms	Elementary particle
Proton	Positive , , 1.602 x 10^-19 coulombs (C)	1.6726 x 10^-27	1 down quark 2 up quarks
Neutron	No …	1.6750 x 10^-27	2 Down Quarks 1 up quark

Measurement :

“The activity in which we compare something with some standard is called measurement”

Exercise Short Questions

Q No 1: Name the convenient unit you will use to measure (a). Width of a book (b).length of room (c).diameter of a wire_

Ans: the convenient units we will use for the measurement of each object is i.e.

For measuring width of book we will use centimeter “cm”_

For measuring length of room we will use foot or meter “m”_

For measuring diameter of wire we will use millimeter “mm”_

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Q No 2: name the most convenient units of mass you will use to measure to measure

(a).mass of candy ,(b).bag of sugar, (c).mass of cricket ball

Ans: the convenient units we will use for the measurement of each object are i.e.

For measuring candy we will use milligram “mg”_

For measuring sugar bag we will use kilogram “kg”_

For measuring cricket ball we will use gram “gm”_

_____________ ___ __________

Q No 3: Name seven SI basic units of measurement?

Ans: System International SI define the basic Physical quantities as,

“Those physical quantities in terms of which other physical quantities are defined “

There are seven Basic Physical quantities which are given below in table

Physical Quantities	Units Name	Units Symbols
Length	Meter	m
Mass	Kilogram	Kg
Time	Second	s
Electric Current	Ampere	A
Temperature	Kelvin	K
Luminous Intensity	Candela	cd
Amount of Substance	Mole	mol

___________________ ____________

Q No 4: choose the basic Physical quantities and derived physical quantities of fallowing, temperature, volume, time, aria, density, length.

Ans: Basic Physical Quantities :

“Those physical quantities in terms of which other physical quantities are defined “

The basic physical quantities are Temperature, Time and Length.

Derived Physical Quantities:

“Those quantities which are defined in term of Basic Physical quantities”

The derived Physical quantities are volume, aria, and density.

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Q No 4: why aria is called derived Quantity?

Ans: As we know that derived quantities are obtained from the combination of base physical quantities

So in case of aria ,we can say that aria is also a derived physical quantity because it is also obtained by the product of two Lengths

Mathematically

Aria = Length X width

Aria = L1 X L 2 _________(1)

So from equation (1) we can say Aria is derived Physical quantity

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Q No 5: digital stop watch is more commonly used in physics experiments .why?

Ans: Digital stopwatch is commonly used in physics experiments because

it is readily available
it is cheap one
it is easy to use
and has no parallax error compared to analogue kinds

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Q No 6: give the name and symbols of the prefix used to represent the fallowing values

(a).10^-3 (b). 10^-6 (c).10⁹ (d). 10^-12

Ans: table for name and symbols of given prefix are as i.e.

Prefix	Name	Symbols
10^-3	mili	m
10^-6	micro	µ
10⁹	giga	G
10^-12	pico	p

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Q No 8: how much water in units of liter can fill a water tank of 1 m³capacity? Explain.

Ans: as we know that one cubic meter “m^3”is equal to one thousand “1000 “ liters so by this we can conclude that the tank of capacity 1 m³ will hold the water of volume one thousand (1000) liters

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Q No 9: Explain the statement “A micrometer Screw Gauge measures more accurately then a vernier caliper “.

Ans: accuracy depends upon the least count of the instrument that is used in measurement, in case of vernier caliper we can only measure up to 0.1mm (which is least count of vernier caliper) where as in case of micrometer screw gauge we can measure up to 0.01 mm (which is least count of screw gauge)

So in screw gauge we can measure more accurately that is up to 2 decimal points hence it is better than vernier caliper

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Q No 10: if Zero of circular scale above datum line then explain how we can correct our reading ?

Ans: if Zero of Circular scale moves above from datum line of

Main scale then it means there is negative zero error in the Micrometer

Screw Gauge this also cause an error in our reading. So we can

Correct our reading simply by adding the value of error in our final calculation.

Q No 11:how can we find the volume of small pebble with the help of measuring cylinder ?

Ans: the measuring cylinder is made up of transparent plastic or glass and has vertical scale in milliliter (ml) or cubic centimeter (Cm³).

We can find the volume of small pebble by using measuring cylinder i.e.

· Pure the water into the cylinder and note the reading on scale marked on cylinder

· Put the pebble into the cylinder slowly

· Level of water will increase in the cylinder

· Now read new reading from scale marked on cylinder

· So volume of pebble will be the difference between initial and final reading on scale

Mathematically:

Volume of Pebble =Final Volume – Initial volume

V_b = V_f- V_i
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___________________Comprehensive Questions __________ _______________________

Q No 1: write complete note on science and history of science?

Ans: Science: the word Science is derived from Latin word Scientia which means knowledge . so we can define the science as,

“The knowledge gained through observations and experiments is called science”

History Of Science:

The man has always been inspired by world of nature .he always try to find out the secrets of nature and remained in search of reality and truth he observes various phenomenon and try to find their answer by logical way .

Until eighteen century various aspects of natural objects under the single subject called natural philosophy but s the knowledge increase it was divide into study of nonliving material (under physics) and study of living things (under Biology )

We can say science has made the life of man easy. Today due to countless inventions of science we can save our time we an travel through large distance in minutes or hours we can connect with world anywhere any time in the world

No doubt science have lot of benefits but in other wise science have also disadvantages that creates problems in man life like deadly weapons ,environmental pollution and road accidents .

Q No 2: how would you define a physics describe its main branches?

History:

The word 'physics' itself is traced back to the Greek word phusika, meaning 'natural things.' It was in the ancient Greeks' study of philosophy and the natural world around them that how the science of physics was first born. Asking philosophical questions about why the world works the way it does led to investigation of the world in order to determine those answers. Since then, the definition of physics has changed from the more vague philosophical beginnings as a study of nature to the study of matter and energy and how they interact with one another.

Definition:

Physics is defined as “Branch of natural science that deal with the study of matter ,energy and their mutual relationship”

For Example:

Study of Motion of object under influence of some forces .

To study the wave nature of light .

Study the motion of planets etc.

are the example of physics .

Branches :

Five main branches of Physics given below

1. Mechanics: It deals with the motion of objects (point or objects with small masses) under the influence of force _
2. Optics: It deals with the formation of images using mirrors and lenses
3. Electrodynamics and Magnetism: It deals with the study of charged particles and their magnetic behavior
4. Nuclear Physics (Quantum Physics): It deals with atomic collisions and nuclear fission and fusion_and reaction_photoelectric_effect.
5. Thermodynamics: It deals with transformation of heat engines.

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Q No 2: give the points that physics linked with Biology, Chemistry, geography and Astronomy?

Ans: physics have great applications in almost every field of life today, relation of physics with some other fields are,

With Biology:

Also known as Biophysics, Biophysics is an interdisciplinary science that applies the approaches and methods of physics to study biological systems. Biophysics covers all scales of biological organization, from molecular to organismic and populations.

With Chemistry : called Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of laws and concepts of physics. It applies the principles, practices and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics and dynamics, equilibrium.

Some of the relationships that physical chemistry strives to resolve include the effects of:

Intermolecular forces that act upon the physical properties of materials (plasticity, tensile strength, surface tension in liquids).

Reaction kinetics on the rate of a reaction.

The identification of ions and the electrical conductivity of materials.

Interaction of one body with another in terms of quantities of heat and work called thermodynamics.

Transfer of heat between a chemical system and its surroundings during change of phase or chemical reaction taking place called thermochemistry

With Geography:

Link of physics with geography is also known as Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation.[1] However, modern geophysics organizations use a broader definition that includes the water cycle including snow and ice; fluid dynamics etc.

With Astronomy :

Combination of physics with astronomy is also termed as Astrophysics, is a branch of space science that applies the laws of physics and chemistry to explain the birth, life and death of stars, planets, galaxies, nebulae and other objects in the universe. It has two sibling sciences, astronomy and cosmology, and the lines between them

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Q No 3: Distinguish between basic and derived Physical Quantities?

Ans : Introduction

Experimentation is a core aspect of physics and other physical sciences. Theories and other hypothesis are verified and established as scientific truth by means of experiments conducted. Measurements are an integral part of experiments, where the magnitudes of and the relations amongst different physical quantities are used to verify the truth of the theory or hypothesis tested.

There are very common set of physical quantities that are often measured in physics. These quantities are considered as fundamental quantities by convention. Using the measurements for these quantities and the relations amongst them, other physical quantities can be derived. These quantities are known as derived physical quantities.

Fundamental Quantities(Base Quantities ):

A set of fundamental units are defined in every units system, and the corresponding physical quantities are called the fundamental quantities. Fundamental units are independently defined, and often the quantities are directly measurable in a physical system.

In general, a system of units requires three mechanical units (mass, length, and time). One electrical unit is also required. Even though above set of units may suffice, for convenience few other physical units are considered fundamental. c.g.s (centimeter-gram-second), m.k.s (meter-kilogram second), and f.p.s (feet-pound-second) are formerly used systems with fundamental units.

SI unit system has replaced much of the older units systems. In the SI system of units, by definition, following seven physical quantities are considered as fundamental physical quantities and their units as fundamental physical units.

Quantities	Units	Symbols
Length	meter	m
Mass	kilogram	kg
Time	seconda	s
Electric Current	ampere	A
Temperature	kelvin	k
Amount of Substance	mole	mol
Luminous intensity	candela	cd

Derived Quantities:

Derived quantities are formed by product of powers of fundamental units. In other words, these quantities can be derived using fundamental units. These units are not defined independently; they depend on the definition of other units. Quantities attached to derived units are called derived quantities.

Physical Quantity	Unit	Symbol
force	Newton	N	-	m·kg·s^-2
pressure, stress	Pascal	Pa	N/m²	m^-1·kg·s^-2
electric charge, quantity of electricity	Coulomb	C	-	A·s
electric potential difference, electromotive force	Volt	V	W/A	m²·kg·s^-3·A^-1

For example, consider the vector quantity of speed. By measuring the distance traveled by an object and the time taken, the average speed of the object can be determined. Therefore, speed is a derived quantity. Electric charge is also a derived quantity where it is given by the product of current flow and time taken. Each derived quantity has derived units. Derived quantities can be formed.

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Q No 4: what is meant by significant figure of measurement? What are the main points keeping in mind while determining the significant figures of measurement?

Ans: Significant Figures: Significant figure is defined as

“Each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first non-zero digit”

“The number of accurately known figure and first doubtful figure is known as significant figure “

Explanation:

There are two types of values in measurements that is “exact values” in which there is no doubt and ambiguity, like 3 pencils and 2 books they are exact in number and have no doubt in counting. Beside that there are some measurements in which there is uncertainty up to some extent so there is a doubt that is normally happens when we measure the things beyond the least count of instrument

For example least count of scale is graduated in mm

Suppose we note that the length of penciled is greater then the length of 6.7 cm and greater than the 6.8 cm

We estimate that the length of pencil is 6.75 cm . now this length is accurate up to 6.7 but least friction of mm has been guessed there is chance of error in least figure it is called doubtful figure .

So significant with first doubtful figure is called significant figure .

Rules For Significant Figures:

· All Natural numbers are significant figures i.e. 1 to 9 and combination of these numbers_

Case 1: if there involves Zero “0”_

1. Zero between non zero digits are significant
· e.g. 2004 (Four S.F),190.9(Four S.F),2.01(Three S.F),300004 (Six S.F) _
2. zero to the left of significant figure(non zero digits )is not significant _
· e.g. 0007 (One S.F), 07(One S.F),00345(three S.F)_
3. zero to right of significant figures (non zero digits ) are significant _
· e.g. 7000 (four SF), 300,00(five SF)_

Case 1: if there involves Decimal Point _

1. zero to left side of decimal point is not significant _
· e.g. 0.4 (one SF ), 000.3(one SF) ,000.34(2 SF )
2. zero to the right side of decimal point may or may not be significant_
· e.g. 0.03(one SF ),0.007 (one SF ),0.0456(Two SF ),0.04005(Four SF ),0.500(Three SF )

Q No 5: write a note on Vernier Calipers and Screw Ga

Ans Vernier Calipers

Outlines :

· History_

· Parts _

· Least Count_

· Measuring procedure _

· Zero error and zero correction_

History:

Calipers without a vernier scale originated in ancient China as early as the Qin dynasty (9 AD) . The secondary scale, which contributed extra precision, was invented in 1631 by French mathematician Pierre Vernier (1580–1637). Its use was described in detail in English in Navigation Britannica (1750) by mathematician and historian John Barrow.[3] While calipers are the most typical use of Vernier scales today, they were originally developed for angle-measuring instruments such as astronomical._

Parts:

The vernier caliper consists of a main scale and a vernier scale, and enables readings with a precision of 1/200 cm.main scale is fitted with Jaws C and D on either side, with the straight edges connecting C and D vertically to the main scale forming a right angle. Simultaneously, Jaws E and F are fitted on the vernier scale, which moves over the main scale

Least Count:

“The minimum values measured by an instrument s called least count of that instrument “

In case of vernier Caliper least count can be calculated by two ways ,

Least count =1 mm - 0. 9 mm =0.1 mm or 0.01 cm

Or by using formula,

Measuring Procedure:

. When the jaws of the main and the vernier scales contact each other, the zeros of both scales should coincide. If the zeros do not coincide, a zero point calibration must be performed instantly. The distance between C and E or between D and F is the length of the object that is being measured.

Suppose we ant to calculate the diameter of a solid cylinder we will use the fallowing methods

ð Step 1: note the least count of vernier caliper

ð Step 2: close jaws fully without any object in it and note, is there any zero error or not?

a. If zero of main scale coincides with zero of vernier scale then there is no error

b. Id it do not coincides then there is an error either positive or negate

ð Step 3. If there is no error then fix the cylinder in jaws and tight the vernier caliper

ð Step 4: suppose zero of vernier scale coincides with at the point that is Right to 1.9 cm and to the left of 2.0 cm (between 1.9 and 2.0 cm) ,so required length will be somewhat greater then 1.9 cm _

ð Step 5: to add fraction see which division of vernier scale coincides exactly with main scale division, suppose forth division of vernier sale match with first coming division (left to right ) of main scale division

ð Step 6: multiply least count with 4 and add to the result obtained from above measurement i.e. 1.9 so,

ð 0.01* 4= 0.04 cm

ð 1.9 cm+ 0.04 cm

ð 1.94 cm _________(1)

Hens it is required calculation _

Ø Zero Error and Zero Correction :

If zero of bot scales don’t coincides it means there exist an error called zero error,which can be either Positive zero error or negative zero error_

Positive zero error: Positive zero error occurs when the ‘0’ marking of the vernier scale appears after the ‘0’ marking of the main scale. The error is +x cm. To correct the reading, we subtract the error value from the measurement.
Negative zero error occurs when the ‘0’ marking of the vernier scale appears before the ‘0’ marking of the main scale. The error is -(0.1-y) cm. To correct the reading, we subtract the error from the measurement.
Negative zero error: Negative zero error occurs when the ‘0’ marking of the vernier scale appears before the ‘0’ marking of the main scale. The error is -(0.1-y) cm. To correct the reading, we subtract the error from the measurement.

Screw Gauge

Outlines :

· History_
· Parts _
· Least Count_
· Measuring procedure_
Zero error and zero correction_

History:

The first ever micrometric screw was invented by William Gascoigne in the 17th century, as an enhancement of the vernier; it was used in a telescope to measure angular distances between stars and the relative sizes of celestial objects.

Handheld micrometer-screw calipers was invented by Jean Laurent Palmer of Paris in 1848

In 1888 Edward W. Morley added to the precision of micrometric measurements and proved their accuracy in a complex series of experiments.

Parts _

Micrometer is composed of:

· Frame

The C-shaped body that holds the anvil and barrel in constant relation to each other The frame is heavy and consequently has a high thermal mass, to prevent substantial heating up by the holding hand/fingers. It is often covered by insulating plastic plates which further reduce heat transference.
Explanation: if one holds the frame long enough so that it heats up by 10 °C, then the increase in length of any 10 cm linear piece of steel is of magnitude 1/100 mm. For micrometers this is their typical accuracy range.

· Anvil:

The shiny part that the spindle moves toward, and that the sample rests against.

· Sleeve / barrel / stock:

The stationary round component with the linear scale on it. Sometimes vernier markings.

· Lock nut / lock-ring / thimble lock:

The knurled component (or lever) that one can tighten to hold the spindle stationary, such as when momentarily holding a measurement.

· Screw:

(not seen) The heart of the micrometer, as explained under "Operating principles". It is inside the barrel. This references the fact that the usual name for the device in German is Messschraube, literally "measuring screw".

· Spindle

The shiny cylindrical component that the thimble causes to move toward the anvil.

· Thimble

The component that one's thumb turns. Graduated markings.

· Ratchet stop

Device on end of handle that limits applied pressure by slipping at a calibrated torque.

Pitch of the Screw Gauge:

The pitch of the screw is the distance moved by the spindle per revolution. To find this, the distance advanced by the head scale over the pitch scale for a definite number of complete rotation of the screw is determined.

The pitch can be represented as;

Least Count of the Screw Gauge:

The Least count (LC) is the distance moved by the tip of the screw, when the screw is turned through 1 division of the head scale.

The least count can be calculated using the formula;

Zero Error and Zero Correction:

To get the correct measurement, the zero error must be taken into account. For this purpose, the screw is rotated forward till the screw just touches the anvil and the edge of cap is on the zero mark of the pitch scale. The Screw gauge is held keeping the pitch scale vertical with its zero down wards.
When this is done, anyone of the following three situations can arise:

The zero mark of the circular scale comes on the reference line. In this case, the zero error and the zero correction, both are nil.
The zero mark of the circular scale remains above the reference line and does not cross it. In this case, the zero error is positive and the zero correction is negative depending on how many divisions it is above the reference line.
The zero mark of the head scale is below the reference line. In this case, the zero error is negative and the zero correction is positive depending on how many divisions it is below the reference line.

To find the thickness of the glass plate

The glass plate is gripped between the tip of the screw and the anvil. The PSR and HSR are noted as before.
The thickness of the glass plate is;

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