Title 1_VI_OLY._PHYSICS_WS(UNITS & DIM., VECTORS)_VOL-1.pdf ✅

Olympiad Text Book VI-Physics (Vol-1) Narayana Group of Schools 1 CONTENTS : Introduction to Physics Physical Quantities and units Fundamental and Derived Quantities Multiple and Sub-multiple factors Measurement of length, mass, time Conversion of units Area Volume Density Vernier Callipers UNITS AND DIMENSIONS
VI-Physics (Vol-1) Olympiad Text Book Narayana Group of Schools 2 UNITS AND DIMENSIONS Pierre Vernier (19 August 1580) Pierre Vernier (19 August 1580 at Ornans, Franche-Comté, Spanish Habsburgs (now France) – 14 September 1637 same location) was a French mathematician and instrument inventor. He was inventor and eponym of the vernier scale used in measuring devices. He was born in Ornans, France, in 1580, he was taught science by his father. He later became captain and castellan of the castle at Ornans, for the King of Spain. He was also later councillor and Pierre Vernier director general of moneys in the County of Burgundy. (19 August 1580) KNOW YOUR SCIENTIST SYNOPSIS - 1 INTRODUCTION TO PHYSICS Observe the following events which we come across in our daily life: • How the water entered into coconut even though it had a hard shell ? • How can a large ship which can float in water, but a small stone can not float ? • We see Lightning first and then we hear a thunder. Similarly in Television we here sound first then we see picture why ? • How rain comes ? • Who is catching the Earth for it to rotate ? • How does a flower turns into fruit ? • How can a bird can fly ? Why Human beings can not fly ? • What is there beyond Sun ? • How can Sun gives us Light and Heat ? • Why Stars appear so small ? • Why can’ t Animals speak with Human beings ? There are so many other numerous Questions and Problems which are need to be Answered and to be Solved. The Answers for the above Phenomena is possible only through the study of PHYSICS. Physics is the study of laws of nature. Introduction to Measurement Measurements have an important role not only in physics but also in every branch of science and everywhere in our day-to-day life. Measurement should be made for knowing about the physical quantity. For example, Imagine that you take a piece of cloth to a tailor for stitching a shirt. What will the tailor do ?
Olympiad Text Book VI-Physics (Vol-1) Narayana Group of Schools 3 He will first find ‘how much’ quantity of cloth is required to prepare a shirt for you. To know how much quantity required is called measuring. The act of measuring the quantity required is called measurement. In the above example, the quantity measured by the tailor using a tape is length. Quantity Quantity means size, amount, magnitude or simply stated as the answer for ‘how much?’ or ‘how many?’ Physical Quantity: The quantities which are measurable are called physical quantities. Ex : Length, mass, time, speed, etc. Note : Love, sadness, hatred, affection are not physical quantities because you cannot measure them. The information about a physical quantity, by description of its external properties like colour, taste etc. is incomplete with out knowing its temperature, size (dimensions), which depends on measurement. i.e., with out measurements it is impossible to know about the external properties of any object. So, it becomes necessary to measure it.Thus Measurement is thus the comparison of an unknown quantity with a known constant quantity. This constant quantity which is used to measure the standard physical quantity is called unit. Unit is a standard to measure the physical quantity. Measurement of the physical quantity Measurement of the physical quantity involves two steps. Step 1: Choose the standard value as a unit of measurement (unit) Step 2: Find how many times that unit is contained in the given physical quantity (Numerical Value) i.e., A measurement consists of two parts, the numerical value and the unit. Ex : Length of the table = 5 metre. Here length is the physical quantity 5 is the numerical value and metre is the unit.  Physical quantity = numerical value × unit Note : The number of times a standard quantity is present in a given physical quantity is called Numerical value of physical quantity. Unit : In the early days, people used to measure length with the help of various parts of a body, such as handspan, footspan , arm or cubit etc., Look at a boy measuring the length of a table: Here, the boy is measuring the length of the table using handspan and the length was found to be 8 handspans.
VI-Physics (Vol-1) Olympiad Text Book Narayana Group of Schools 4 We can also say that handspan is present 8 times during the measurement of length of the table.This handspan (a part of the body) which is used to measure the length was called a unit. Ask four students to measure the length of your text book by using palm and note the values. Let them compare the values and find that the values vary as their palms are of different sizes. This indicates that hand measurements like, span, cubit and fathom differ from person to person. But measurement should be the same whoever and wherever it is measured. Standard Unit: Imagine now boy’s father is measuring the length of the table using his handspan. Length of the table measured by his father is found to be 6 handspans whereas length of the table measured by the boy was 8 handspans. So, using handspan as a unit, length found by the boy and his father is not same. Hence, we need a unit which gives same length when used by the boy or his father or infact any one, and this unit is called standard unit. For example, Meter is the standard by which we can measure length, Second is the standard by which we can measure time etc., Note: Magnitude of a physical quantity is constant (does not change with choice of unit) Magnitude Physical Quantity(P) = Numerical value(N) × Unit(U) i.e., P = constant  NU = constant  1 N U  (as p is constant)  N1U1 = N2U2 Example : Height of a girl is 1.2m= 120 cm in 1.2m the unit is m and the numerical value is 1.2. in 120 cm the unit is cm and numerical value is 120. “Think it Over!” gm/cm3 and kg /m3 are the units of density and 1gm/cm3 =1000 kg/m3 . Is the above relation Violating the rule N1U1 =N2U2? System of Units : The scientists all over the world have developed basic set of standard units for measuring various quantities. This set is also known as system of units and named as Standard International System of Units or SI system. At present the system adopted by all the scientists in the world is SI. Some other units still in use are (i) F.P.S system (Foot, Pound,Second) (ii) C.G.S. system (Centimetre, Gram, Second) (iii) M.K.S. system (Metre, Kilogram, Second) MKS CGS Centimeter (cm) Gram (g) FPS Foot (ft) Pound( ) lb Length Mass Time Metre (m) Second (s) Second (s) Kilogram(kg) Second (s) System MKS Centimeter (cm) Gram (g) Foot (ft) Mass Time Fundamental Physical Quantities