Selina Textbook Solutions: Physical Quantities and Measurement | Physics Class 6 ICSE PDF Download

 Page 1


? Synposis 
?  The observation of a phenomenon is made possible by using the five senses: 
sight, smell, touch, hearing and taste. 
?  Our senses are not always reliable. They are subjective. 
?  Sometimes it is necessary to make an exact measurement. 
?  Physics is a science of measurement. 
?  We use instruments to get an exact measurement. 
?  Four basic measurements in our daily life are: measurement of length, 
measurement of mass, measurement of time, and measurement of temperature. 
?  Measurement is basically a process of comparison of the given quantity with a 
standard unit. 
?  For measuring a quantity we need a unit, and then we find the number of times 
that unit is contained in that quantity. 
?  The unit selected for measurement should be of a convenient size and it must not 
change ‘with place or time. 
?  The distance between two fixed points is called length. 
?  The S.I. unit of length is metre (m). Its multiple is kilometre (km), where 1 km = 
1000 m. Its sub multiples are centimetre (cm) and millimetre (mm), where 1 cm = 
10
-2
 m and 1 mm = 10
-3
 m. 
?  The FPS unit of length is foot (ft) and its sub multiple is inch where 1 ft = 12 inch 
and 1 ft = 30.48 cm. 
?  The most common instruments used to measure length are the metre ruler and 
the measuring tape which are marked in cm and mm. 
?  To measure a length accurately with a metre ruler, the scale should be placed 
with its markings close to the object and parallel to its r length. The eye is kept in 
front of and in line with the reading to be taken. 
?  The quantity of matter contained in a body is called its mass. 
?  The S.I. unit of mass is kilogram (kg). Its multiples are quintal and metric tonne. 1 
quintal = 100 kg and 1 metric tonne =10 quintal = 1000 kg. Its sub multiples are 
gram (g) and milligram (mg) where 1 g = 10 kg and lmg = 10
-6
 kg. 
?  The FPS unit of mass is pound (lb) where 1 lb = 453.59 g. 
?  Mass of a body is measured by using a beam balance or an electronic balance. 
?  The interval between two instances or events is called time. 
?  The S.l. unit of time is second (s), 1 s 1 / 86400 of a mean solar day. The C.G.S. 
and F.P.S. unit of time is also second (s). 
? The multiple unit of time are minute (mm), hour (h), day and year where 1 min = 
60 s, 1 h = 3600 s, 1 day = 86400 s and 1 year = 3.15 × 10
7
 s. 
?  The time at any instant is recorded by a pendulum clock or watch and the time 
interval of an event is measured by using a stop watch or a stop clock. 
?  The temperature is the measure of degree of hotness or coldness of a body. 
?  The S.I. unit of temperature is kelvin(K), but the common unit of temperature is 
degree Celsius (°C) and degree fahrenheit (°F). 
?  Doctors use a clinical thermometer to measure the patient’s body temperature. 
?  The normal temperature of a human body is 37°C or 98.6°E 
?  The total surface occupied by an object is called its area. Area is expressed as 
the product of measured length of two sides. 
Page 2


? Synposis 
?  The observation of a phenomenon is made possible by using the five senses: 
sight, smell, touch, hearing and taste. 
?  Our senses are not always reliable. They are subjective. 
?  Sometimes it is necessary to make an exact measurement. 
?  Physics is a science of measurement. 
?  We use instruments to get an exact measurement. 
?  Four basic measurements in our daily life are: measurement of length, 
measurement of mass, measurement of time, and measurement of temperature. 
?  Measurement is basically a process of comparison of the given quantity with a 
standard unit. 
?  For measuring a quantity we need a unit, and then we find the number of times 
that unit is contained in that quantity. 
?  The unit selected for measurement should be of a convenient size and it must not 
change ‘with place or time. 
?  The distance between two fixed points is called length. 
?  The S.I. unit of length is metre (m). Its multiple is kilometre (km), where 1 km = 
1000 m. Its sub multiples are centimetre (cm) and millimetre (mm), where 1 cm = 
10
-2
 m and 1 mm = 10
-3
 m. 
?  The FPS unit of length is foot (ft) and its sub multiple is inch where 1 ft = 12 inch 
and 1 ft = 30.48 cm. 
?  The most common instruments used to measure length are the metre ruler and 
the measuring tape which are marked in cm and mm. 
?  To measure a length accurately with a metre ruler, the scale should be placed 
with its markings close to the object and parallel to its r length. The eye is kept in 
front of and in line with the reading to be taken. 
?  The quantity of matter contained in a body is called its mass. 
?  The S.I. unit of mass is kilogram (kg). Its multiples are quintal and metric tonne. 1 
quintal = 100 kg and 1 metric tonne =10 quintal = 1000 kg. Its sub multiples are 
gram (g) and milligram (mg) where 1 g = 10 kg and lmg = 10
-6
 kg. 
?  The FPS unit of mass is pound (lb) where 1 lb = 453.59 g. 
?  Mass of a body is measured by using a beam balance or an electronic balance. 
?  The interval between two instances or events is called time. 
?  The S.l. unit of time is second (s), 1 s 1 / 86400 of a mean solar day. The C.G.S. 
and F.P.S. unit of time is also second (s). 
? The multiple unit of time are minute (mm), hour (h), day and year where 1 min = 
60 s, 1 h = 3600 s, 1 day = 86400 s and 1 year = 3.15 × 10
7
 s. 
?  The time at any instant is recorded by a pendulum clock or watch and the time 
interval of an event is measured by using a stop watch or a stop clock. 
?  The temperature is the measure of degree of hotness or coldness of a body. 
?  The S.I. unit of temperature is kelvin(K), but the common unit of temperature is 
degree Celsius (°C) and degree fahrenheit (°F). 
?  Doctors use a clinical thermometer to measure the patient’s body temperature. 
?  The normal temperature of a human body is 37°C or 98.6°E 
?  The total surface occupied by an object is called its area. Area is expressed as 
the product of measured length of two sides. 
?  The S.I. unit of area is square metre (m
2
). 
?  One square metre is the area of a square of each side one metre. 
?  The bigger (or multiple) units of area are dam
2
, hectare and square kilometre 
(km
2
), where 1 dam
2
=100 m
2
,1 hectare= 10
4
 m
2
 and 1 km
2
 = 10
6  m 2
 
?  The smaller (or sub multiple) units of area are cm
2
 and mm
2
 where 1cm
2
 = 10
-
4
 m
2
 and 1 mm
2
 = 10
-6  
m
2
 
Test yourself 
A. Objective Questions 
1. Write true or false for each statement 
(a) S.I. unit of temperature is fahrenheit. 
Answer. False 
(b) Every measurement involves two things – a number and a unit 
Answer. True 
(c) Mass is the measure of quantity of matter. 
Answer. True 
(d) The S.I. unit of time is hour. 
Answer. False 
(e) The area can be expressed as the product of length of two sides. 
Answer. Tme 
2. Fill in the blanks 
(a) The S.I. unit of length is metre of time is second of mass is kilogram. 
(b) °C is the unit of temperature. 
(c) 1 metric tonne = 1000 kg 
(d) The zero mark in Celsius thermometer is the melting point of ice 
(e) The thermometer used to measure the human body temperature is called 
the clinical thermometer. 
(f) The normal temperature of human body is 37 °C or 98.6 °F. 
(g) The mass of an object is measured with the help of a beam balance. 
Page 3


? Synposis 
?  The observation of a phenomenon is made possible by using the five senses: 
sight, smell, touch, hearing and taste. 
?  Our senses are not always reliable. They are subjective. 
?  Sometimes it is necessary to make an exact measurement. 
?  Physics is a science of measurement. 
?  We use instruments to get an exact measurement. 
?  Four basic measurements in our daily life are: measurement of length, 
measurement of mass, measurement of time, and measurement of temperature. 
?  Measurement is basically a process of comparison of the given quantity with a 
standard unit. 
?  For measuring a quantity we need a unit, and then we find the number of times 
that unit is contained in that quantity. 
?  The unit selected for measurement should be of a convenient size and it must not 
change ‘with place or time. 
?  The distance between two fixed points is called length. 
?  The S.I. unit of length is metre (m). Its multiple is kilometre (km), where 1 km = 
1000 m. Its sub multiples are centimetre (cm) and millimetre (mm), where 1 cm = 
10
-2
 m and 1 mm = 10
-3
 m. 
?  The FPS unit of length is foot (ft) and its sub multiple is inch where 1 ft = 12 inch 
and 1 ft = 30.48 cm. 
?  The most common instruments used to measure length are the metre ruler and 
the measuring tape which are marked in cm and mm. 
?  To measure a length accurately with a metre ruler, the scale should be placed 
with its markings close to the object and parallel to its r length. The eye is kept in 
front of and in line with the reading to be taken. 
?  The quantity of matter contained in a body is called its mass. 
?  The S.I. unit of mass is kilogram (kg). Its multiples are quintal and metric tonne. 1 
quintal = 100 kg and 1 metric tonne =10 quintal = 1000 kg. Its sub multiples are 
gram (g) and milligram (mg) where 1 g = 10 kg and lmg = 10
-6
 kg. 
?  The FPS unit of mass is pound (lb) where 1 lb = 453.59 g. 
?  Mass of a body is measured by using a beam balance or an electronic balance. 
?  The interval between two instances or events is called time. 
?  The S.l. unit of time is second (s), 1 s 1 / 86400 of a mean solar day. The C.G.S. 
and F.P.S. unit of time is also second (s). 
? The multiple unit of time are minute (mm), hour (h), day and year where 1 min = 
60 s, 1 h = 3600 s, 1 day = 86400 s and 1 year = 3.15 × 10
7
 s. 
?  The time at any instant is recorded by a pendulum clock or watch and the time 
interval of an event is measured by using a stop watch or a stop clock. 
?  The temperature is the measure of degree of hotness or coldness of a body. 
?  The S.I. unit of temperature is kelvin(K), but the common unit of temperature is 
degree Celsius (°C) and degree fahrenheit (°F). 
?  Doctors use a clinical thermometer to measure the patient’s body temperature. 
?  The normal temperature of a human body is 37°C or 98.6°E 
?  The total surface occupied by an object is called its area. Area is expressed as 
the product of measured length of two sides. 
?  The S.I. unit of area is square metre (m
2
). 
?  One square metre is the area of a square of each side one metre. 
?  The bigger (or multiple) units of area are dam
2
, hectare and square kilometre 
(km
2
), where 1 dam
2
=100 m
2
,1 hectare= 10
4
 m
2
 and 1 km
2
 = 10
6  m 2
 
?  The smaller (or sub multiple) units of area are cm
2
 and mm
2
 where 1cm
2
 = 10
-
4
 m
2
 and 1 mm
2
 = 10
-6  
m
2
 
Test yourself 
A. Objective Questions 
1. Write true or false for each statement 
(a) S.I. unit of temperature is fahrenheit. 
Answer. False 
(b) Every measurement involves two things – a number and a unit 
Answer. True 
(c) Mass is the measure of quantity of matter. 
Answer. True 
(d) The S.I. unit of time is hour. 
Answer. False 
(e) The area can be expressed as the product of length of two sides. 
Answer. Tme 
2. Fill in the blanks 
(a) The S.I. unit of length is metre of time is second of mass is kilogram. 
(b) °C is the unit of temperature. 
(c) 1 metric tonne = 1000 kg 
(d) The zero mark in Celsius thermometer is the melting point of ice 
(e) The thermometer used to measure the human body temperature is called 
the clinical thermometer. 
(f) The normal temperature of human body is 37 °C or 98.6 °F. 
(g) The mass of an object is measured with the help of a beam balance. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(a) The symbol of degree Celsius is 
1. °C 
2.  °F 
3.  K 
4.  °K 
(b) lO mm is equal to 
1.  1cm 
2.  1m 
3.  10dm 
4.  10cm 
(c) The amount of surface occupied by an object is called its: 
1.  volume 
2.  area 
3.  mass 
4.  length 
Page 4


? Synposis 
?  The observation of a phenomenon is made possible by using the five senses: 
sight, smell, touch, hearing and taste. 
?  Our senses are not always reliable. They are subjective. 
?  Sometimes it is necessary to make an exact measurement. 
?  Physics is a science of measurement. 
?  We use instruments to get an exact measurement. 
?  Four basic measurements in our daily life are: measurement of length, 
measurement of mass, measurement of time, and measurement of temperature. 
?  Measurement is basically a process of comparison of the given quantity with a 
standard unit. 
?  For measuring a quantity we need a unit, and then we find the number of times 
that unit is contained in that quantity. 
?  The unit selected for measurement should be of a convenient size and it must not 
change ‘with place or time. 
?  The distance between two fixed points is called length. 
?  The S.I. unit of length is metre (m). Its multiple is kilometre (km), where 1 km = 
1000 m. Its sub multiples are centimetre (cm) and millimetre (mm), where 1 cm = 
10
-2
 m and 1 mm = 10
-3
 m. 
?  The FPS unit of length is foot (ft) and its sub multiple is inch where 1 ft = 12 inch 
and 1 ft = 30.48 cm. 
?  The most common instruments used to measure length are the metre ruler and 
the measuring tape which are marked in cm and mm. 
?  To measure a length accurately with a metre ruler, the scale should be placed 
with its markings close to the object and parallel to its r length. The eye is kept in 
front of and in line with the reading to be taken. 
?  The quantity of matter contained in a body is called its mass. 
?  The S.I. unit of mass is kilogram (kg). Its multiples are quintal and metric tonne. 1 
quintal = 100 kg and 1 metric tonne =10 quintal = 1000 kg. Its sub multiples are 
gram (g) and milligram (mg) where 1 g = 10 kg and lmg = 10
-6
 kg. 
?  The FPS unit of mass is pound (lb) where 1 lb = 453.59 g. 
?  Mass of a body is measured by using a beam balance or an electronic balance. 
?  The interval between two instances or events is called time. 
?  The S.l. unit of time is second (s), 1 s 1 / 86400 of a mean solar day. The C.G.S. 
and F.P.S. unit of time is also second (s). 
? The multiple unit of time are minute (mm), hour (h), day and year where 1 min = 
60 s, 1 h = 3600 s, 1 day = 86400 s and 1 year = 3.15 × 10
7
 s. 
?  The time at any instant is recorded by a pendulum clock or watch and the time 
interval of an event is measured by using a stop watch or a stop clock. 
?  The temperature is the measure of degree of hotness or coldness of a body. 
?  The S.I. unit of temperature is kelvin(K), but the common unit of temperature is 
degree Celsius (°C) and degree fahrenheit (°F). 
?  Doctors use a clinical thermometer to measure the patient’s body temperature. 
?  The normal temperature of a human body is 37°C or 98.6°E 
?  The total surface occupied by an object is called its area. Area is expressed as 
the product of measured length of two sides. 
?  The S.I. unit of area is square metre (m
2
). 
?  One square metre is the area of a square of each side one metre. 
?  The bigger (or multiple) units of area are dam
2
, hectare and square kilometre 
(km
2
), where 1 dam
2
=100 m
2
,1 hectare= 10
4
 m
2
 and 1 km
2
 = 10
6  m 2
 
?  The smaller (or sub multiple) units of area are cm
2
 and mm
2
 where 1cm
2
 = 10
-
4
 m
2
 and 1 mm
2
 = 10
-6  
m
2
 
Test yourself 
A. Objective Questions 
1. Write true or false for each statement 
(a) S.I. unit of temperature is fahrenheit. 
Answer. False 
(b) Every measurement involves two things – a number and a unit 
Answer. True 
(c) Mass is the measure of quantity of matter. 
Answer. True 
(d) The S.I. unit of time is hour. 
Answer. False 
(e) The area can be expressed as the product of length of two sides. 
Answer. Tme 
2. Fill in the blanks 
(a) The S.I. unit of length is metre of time is second of mass is kilogram. 
(b) °C is the unit of temperature. 
(c) 1 metric tonne = 1000 kg 
(d) The zero mark in Celsius thermometer is the melting point of ice 
(e) The thermometer used to measure the human body temperature is called 
the clinical thermometer. 
(f) The normal temperature of human body is 37 °C or 98.6 °F. 
(g) The mass of an object is measured with the help of a beam balance. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(a) The symbol of degree Celsius is 
1. °C 
2.  °F 
3.  K 
4.  °K 
(b) lO mm is equal to 
1.  1cm 
2.  1m 
3.  10dm 
4.  10cm 
(c) The amount of surface occupied by an object is called its: 
1.  volume 
2.  area 
3.  mass 
4.  length 
(d) A metre ruler is graduated in: 
1.  m 
2.  cm 
3.  mm 
4.  km 
(e) A thermometer is graduated in: 
1.  kelvin 
2.  °C 
3.  g 
4.  cm 
B. Short/Long Answer Questions 
Question 1. 
What is measurement? How is a measurement expressed? 
Answer: 
Measurement is a comparison of an unknown quantity with a known fixed quantity of the 
same kind. 
The value obtained on measuring a quantity is called its magnitude. The magnitude of a 
quantity is expressed as numbers in its unit. 
Question 2. 
State two characteristics of a unit. 
Answer: 
Two characteristics of a unit are 
1.  It should be of convenient size. 
2.  It must be universally accepted, i. e. its value must remain same at all places and 
at all times. 
Question 3. 
Name four basic measurements in our daily life. 
Answer: 
In our daily life we measure the following four basic physical quantities. 
1.  Length 
2.  Mass 
3.  lime 
4.  Temperature 
Page 5


? Synposis 
?  The observation of a phenomenon is made possible by using the five senses: 
sight, smell, touch, hearing and taste. 
?  Our senses are not always reliable. They are subjective. 
?  Sometimes it is necessary to make an exact measurement. 
?  Physics is a science of measurement. 
?  We use instruments to get an exact measurement. 
?  Four basic measurements in our daily life are: measurement of length, 
measurement of mass, measurement of time, and measurement of temperature. 
?  Measurement is basically a process of comparison of the given quantity with a 
standard unit. 
?  For measuring a quantity we need a unit, and then we find the number of times 
that unit is contained in that quantity. 
?  The unit selected for measurement should be of a convenient size and it must not 
change ‘with place or time. 
?  The distance between two fixed points is called length. 
?  The S.I. unit of length is metre (m). Its multiple is kilometre (km), where 1 km = 
1000 m. Its sub multiples are centimetre (cm) and millimetre (mm), where 1 cm = 
10
-2
 m and 1 mm = 10
-3
 m. 
?  The FPS unit of length is foot (ft) and its sub multiple is inch where 1 ft = 12 inch 
and 1 ft = 30.48 cm. 
?  The most common instruments used to measure length are the metre ruler and 
the measuring tape which are marked in cm and mm. 
?  To measure a length accurately with a metre ruler, the scale should be placed 
with its markings close to the object and parallel to its r length. The eye is kept in 
front of and in line with the reading to be taken. 
?  The quantity of matter contained in a body is called its mass. 
?  The S.I. unit of mass is kilogram (kg). Its multiples are quintal and metric tonne. 1 
quintal = 100 kg and 1 metric tonne =10 quintal = 1000 kg. Its sub multiples are 
gram (g) and milligram (mg) where 1 g = 10 kg and lmg = 10
-6
 kg. 
?  The FPS unit of mass is pound (lb) where 1 lb = 453.59 g. 
?  Mass of a body is measured by using a beam balance or an electronic balance. 
?  The interval between two instances or events is called time. 
?  The S.l. unit of time is second (s), 1 s 1 / 86400 of a mean solar day. The C.G.S. 
and F.P.S. unit of time is also second (s). 
? The multiple unit of time are minute (mm), hour (h), day and year where 1 min = 
60 s, 1 h = 3600 s, 1 day = 86400 s and 1 year = 3.15 × 10
7
 s. 
?  The time at any instant is recorded by a pendulum clock or watch and the time 
interval of an event is measured by using a stop watch or a stop clock. 
?  The temperature is the measure of degree of hotness or coldness of a body. 
?  The S.I. unit of temperature is kelvin(K), but the common unit of temperature is 
degree Celsius (°C) and degree fahrenheit (°F). 
?  Doctors use a clinical thermometer to measure the patient’s body temperature. 
?  The normal temperature of a human body is 37°C or 98.6°E 
?  The total surface occupied by an object is called its area. Area is expressed as 
the product of measured length of two sides. 
?  The S.I. unit of area is square metre (m
2
). 
?  One square metre is the area of a square of each side one metre. 
?  The bigger (or multiple) units of area are dam
2
, hectare and square kilometre 
(km
2
), where 1 dam
2
=100 m
2
,1 hectare= 10
4
 m
2
 and 1 km
2
 = 10
6  m 2
 
?  The smaller (or sub multiple) units of area are cm
2
 and mm
2
 where 1cm
2
 = 10
-
4
 m
2
 and 1 mm
2
 = 10
-6  
m
2
 
Test yourself 
A. Objective Questions 
1. Write true or false for each statement 
(a) S.I. unit of temperature is fahrenheit. 
Answer. False 
(b) Every measurement involves two things – a number and a unit 
Answer. True 
(c) Mass is the measure of quantity of matter. 
Answer. True 
(d) The S.I. unit of time is hour. 
Answer. False 
(e) The area can be expressed as the product of length of two sides. 
Answer. Tme 
2. Fill in the blanks 
(a) The S.I. unit of length is metre of time is second of mass is kilogram. 
(b) °C is the unit of temperature. 
(c) 1 metric tonne = 1000 kg 
(d) The zero mark in Celsius thermometer is the melting point of ice 
(e) The thermometer used to measure the human body temperature is called 
the clinical thermometer. 
(f) The normal temperature of human body is 37 °C or 98.6 °F. 
(g) The mass of an object is measured with the help of a beam balance. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(a) The symbol of degree Celsius is 
1. °C 
2.  °F 
3.  K 
4.  °K 
(b) lO mm is equal to 
1.  1cm 
2.  1m 
3.  10dm 
4.  10cm 
(c) The amount of surface occupied by an object is called its: 
1.  volume 
2.  area 
3.  mass 
4.  length 
(d) A metre ruler is graduated in: 
1.  m 
2.  cm 
3.  mm 
4.  km 
(e) A thermometer is graduated in: 
1.  kelvin 
2.  °C 
3.  g 
4.  cm 
B. Short/Long Answer Questions 
Question 1. 
What is measurement? How is a measurement expressed? 
Answer: 
Measurement is a comparison of an unknown quantity with a known fixed quantity of the 
same kind. 
The value obtained on measuring a quantity is called its magnitude. The magnitude of a 
quantity is expressed as numbers in its unit. 
Question 2. 
State two characteristics of a unit. 
Answer: 
Two characteristics of a unit are 
1.  It should be of convenient size. 
2.  It must be universally accepted, i. e. its value must remain same at all places and 
at all times. 
Question 3. 
Name four basic measurements in our daily life. 
Answer: 
In our daily life we measure the following four basic physical quantities. 
1.  Length 
2.  Mass 
3.  lime 
4.  Temperature 
Question 4. 
What are the S.I. units of 
1.  mass 
2.  length 
3.  time and 
4.  temperature. Write their names and symbols. 
Answer: 
S.I. units are as follows 
 
Question 5. 
Define one metre, the S.I. unit of length. State its one multiple and one sub multiple. 
Answer: 
One metre is defined as the distance travelled by light in air in  of a second 
Multiple of metre = Kilometre 
Submultiple of metre = Centimetre 
Question 6. 
Convert the following quantities as indicated  
(a) 12 inch = ft 
(b) 1 ft = cm 
(c) 20 cm = m 
(d) 4.2 m = cm 
(e) 0.2 km = m 
(f) 0.2 cm = mm 
(g) 1 yard = m 
Answer: 
(a) l2 inch 1 ft 
(b) 1ft = 30.48cm