Dear viewers, I have tried to do my best for the sake of students so that they can secure more marks in their examinations.
I am very much inspired by “Byjus”, “Physics Walah”, “Vedantu” and “Learn CBSE” sites. If you feel that I have done for the ease and support of students then you must comment for the appreciations or suggestions.
Thank You.
Physical Quantities and Measurement Chapter 1
Class 7 - Concise Physics (ICSE)
Selina Publication
If
anyone needs questions or Answers, here is the solution…..
Send
your question by Email and I will return just with answers at Rs. 10/- per
chapter only.
Important Terms with Definitions:
Length: The distance from point A to point B is known as length.
Its S.I. nit is metre (m).
Time: is the interval of occurrence of an event. Its S.I. unit
is second (s).
Mass: Mass is the quantity of matter contained in the body. Its
S.I.unit is kilogram (kg)
Temperature: is a quantity that measures the hotness or coldness of a body.
S.I. unit is Kelvin (K).
Volume: is defined as the
amount of space occupied by any three-dimensional solid.
These solids can be a cube, a cuboid, a cone, a cylinder
or a sphere. Different shapes
have different volumes.
Density: is defined as the mass of a unit volume of that substance.
S.I. unit is kg/m3
==============================================
(A) Multiple Choice
Questions Answers:
Question 1
Pick the correct option:
(a) One litre is equal to:
- 1 cm3
- 1 m3
- 10-3 cm3
- 10-3 m3
Answer
10-3 m3
Reason — 1
litre = 10-3 m3
Pick the correct option:
(b) A metallic piece
displaces water of volume 15 mL. The volume of piece is:
- 15 cm3
- 15 m3
- 15 x 103 cm-3
- 15 x 103 cm3
Answer
15 cm3
Reason —
Volume of body is equal to volume of liquid displaced = 15 mL.
1 mL = 1 cm3, so 15 mL = 15 cm3.
Pick the correct option:
(c) A piece of paper
of dimensions 1.5 m x 20 cm has area:
- 30 m2
- 300 cm2
- 0.3 m2
- 3000 m3
Answer
0.3 m2
Reason — 20
cm = 0.2 m
Area of paper = 1.5 m x 0.2 m = 0.3 m2
Pick the correct option:
(d) The correct
relation is:
- d = M x V
- M = d x V
- V = d x M
- d = M + V
Answer
M = d x V
Reason —
Mass = Volume x density
Pick the correct option:
(e) The density of
alcohol is 0.8 g cm-3. In S.I. unit, it will be:
- 0.8 kg m-3
- 0.0008 kg m-3
- 800 kg m-3
- 8 x 103 kg m-3
Answer
800 kg m-3
Reason — 1
g cm-3 = 1000 kg m-3
So 0.8 g cm-3 = 800 kg m-3
Pick the correct option:
(f) The density of
aluminium is 2.7 g cm-3 and of brass is 8.4 g cm-3.
For the same mass, the
volume of:
- both will be same
- aluminium will be less than that of brass
- aluminium will be more than that of brass
- nothing can be said
Answer
aluminium will be more than that of brass
Reason —
For a given mass of a substance, volume is inversely proportional to density.
As density of aluminium is less than that of brass, so volume of aluminium will
be more than that of brass.
Pick the correct option:
(g) A block of wood
of density 0.8 g cm-3 has a volume of 60 cm3. The
mass of block will be:
- 60.8 g
- 75 g
- 48 g
- 0.013 g
Answer
48 g
Reason —
Mass = density x volume
= 0.8 x 60
= 48 g
So, mass of block is 48 g.
Pick the correct option:
(h) The correct relation
for speed is:
- Speed = distance x time
- Speed = distancetimetimedistance
- Speed = timedistancedistancetime
- Speed = 1distance x timedistance x time1
Answer
Speed = distance/time
Reason —
Speed of a body = distance travelled by the body
at unit time.
Pick the correct option:
(i) A boy travels a
distance 150 m in 1 minute. His speed is:
- 150 m s-1
- 2.5 m s-1
- 25 m s-1
- 9 m s-1
Answer
2.5 m s-1
Reason —
time = 1 min = 60 sec, distance = 150 m
Speed=distance/time
Speed=150/60
Speed = 2.5 m s-1
Pick the correct option:
(j) The density of a
substance …………. With the increase in the
temperature .
- increase
- decrease
- remains same
- none of the above
Answer
Decrease
Reason — Yes, when
heating a substance causes molecules to speed up and spread slightly further apart,
occupying a larger volume that results in a decrease in density.
Question 2
Fill in the blanks:
(a) 1 m3 = ............... cm3
(b) The volume of an irregular solid is determined by the
method of ............... .
(c) Volume of a cube = ............... .
(d) The area of an irregular lamina is measured by using a
............... .
(e) Mass = density x ............... .
(f) The S.I. unit of density is ............... .
(g) 1 g cm-3 = ............... kg m-3.
(h) 36 km h-1 = ............... m s -1.
(i) Distance travelled D = ............... x time t.
Answer
(a) 106
(b) displacement of liquid
(c) (one side)3
(d) graph paper
(e) volume
(f) kg m-3
(g) 1000
(h) 10
(i) speed v
Write True/False
Question 3
Write True/False for the given sttements:
(a) The S.I. unit of
volume is litre.
(b) A measuring beaker of capacity 200 mL can measure only
the volume of 200 mL of a liquid.
(c) cm2 is a smaller unit of area than m2.
(d) Equal volumes of two different substances have equal
masses.
(e) The S.I. unit of density is g cm-3.
(f) 1 g cm-3 = 1000 kg m-3.
(g) The density of water is maximum at 4°C.
(h) The speed 5 m s-1 is less than 25 km h-1.
(i) The S.I. unit of speed is m s-1.
Answer
(a) False
Correct Statement — The S.I. unit of volume is cubic metre (m3).
(b) True
(c) True
(d) False
Correct Statement — Equal volumes of two different substances have
different masses.
(e) False
Correct Statement — The S.I. unit of density is kg m-3.
(f) True
(g) True
(h) True
(i) True
Question 4
Match the following:
|
Column A |
Column B |
|
(a) Volume of a liquid |
(i) kg m-3 |
|
(b) Area of a leaf |
(ii) m3 |
|
(c) S.I. unit of volume |
(iii) graph paper |
|
(d) S.I. unit of density |
(iv) m s-1 |
|
(e) S.I. unit of speed |
(v) measuring cylinder |
Answer
|
Column A |
Column B |
|
(a) Volume of a liquid |
(v) measuring cylinder |
|
(b) Area of a leaf |
(iii) graph paper |
|
(c) S.I. unit of volume |
(ii) m3 |
|
(d) S.I. unit of density |
(i) kg m-3 |
|
(e) S.I. unit of speed |
(iv) m s-1 |
(B) Short Questions Answers:
Question 1
Define the term volume of an object.
Answer
The space occupied by an object is called its volume.
Question 2
State and define the S.I. unit of volume.
Answer
The S.I. unit of volume is cubic metre (m3). One
cubic metre is the volume of a cube with each side 1 metre long.
Question 3
State two smaller units of volume. How are they related to
the S.I. unit?
Answer
The two smaller units of volume are cubic centimetre (cm3),
cubic decimetre (dm3).
1 m3 = 1 m x 1 m x 1 m
= 100 cm x 100 cm x 100 cm
= 1000000 cm3
= 106 cm3
So, 1 m3 = 106 cm3
1 m3 = 1 m x 1 m x 1 m
= 10 dm x 10 dm x 10 dm
= 1000 dm3
= 103 dm3
So, 1 m3 = 103 dm3
Question 4
How will you determine the volume of a cuboid? Write the
formula you will use.
Answer
The volume of a cuboid is determined by finding its three
dimensions i.e., length, breadth and height.
The formula for volume of cuboid is length x breadth x
height
Question 5
You are required to take out 200 mL of milk from a bucket
full of milk. How will you do it?
Answer
A measuring beaker of 200 mL is used to measure 200 mL of
milk from a bucket full of milk.
- Take a measuring beaker of 200 mL, wash and dry it.
- Immerse the beaker inside the bucket full of milk.
- Fill the beaker completely with the milk.
- Take out the beaker from bucket gently so that no milk
splashes out.
- Pour the milk from measuring beaker into another empty
vessel.
Question 6
Define the term density of a substance.
Answer
The density of a substance is defined as the mass of a unit
volume of that substance.
Question 7
State the S.I. and C.G.S. units of density. How are they
related?
Answer
The S.I. unit of density is kg m-3 and its
C.G.S. unit is g cm-3.
1 g cm-3 = 1000 kg m-3.
Question 8
The density of brass is 8.4 g cm-3. What do you
mean by the statement?
Answer
The statement means one cubic centimeter volume of brass has
mass of 8.4 g.
Question 9
Arrange the following substances in order of their
increasing density:
- iron
- cork
- brass
- water
- mercury
Answer
Cork < Water < Iron < Brass < Mercury.
Question 10
How does the density of water change when:
(a) it is heated from 0°C to 4°C,
(b) it is heated from 4°C to 10°C ?
Answer
(a) Water when heated from 0°C to 4°C, it contracts so
density of water increases and becomes maximum at 4°C.
(b) When water is heated from 4°C to 10°C it expands, so
density decreases.
Question 11
Write the density of water at 4°C.
Answer
The density of water at 4°C is 1 g cm-3 or
1000 kg m-3.
Question 12
Explain the meaning of the term speed.
Answer
Speed of the body is distance travelled by the body in unit
time. It tells us about the motion of the body i.e. how fast or slow it is
moving.
Question 13
Write the S.I. unit of speed.
Answer
The S.I. unit of speed is metre per second (m s-1).
Question 14
A car travels with a speed 12 m s-1, while a
scooter travels with a speed 36 km h-1. Which of the two travels
faster?
Answer
Speed of car = 12 m s-1
Speed of scooter = 36 km h-1
1 km h-1 = 518185 m s-1
36 km h-1 = 36 x 518185 = 10 m s-1
So speed of scooter = 10 m s-1
So car travels faster than scooter; since speed of car is
more than that of scooter.
Question 1
Name two devices which are used to measure the volume of an
object. Draw their neat diagrams.
Answer
The two devices which are used to measure the volume of an
object are:
- Measuring cylinder
- Measuring beaker
Question 2
How can you determine the volume of an irregular solid (say
a piece of brass)? Describe in steps with neat diagrams.
Answer
The volume of an irregular solid can be measured by using a
measuring cylinder by the method of displacement of liquid.
- Place a measuring cylinder on a flat horizontal
surface.
- Fill it partially with water.
- Note the reading of water level very carefully. Let it
be V1.
- Now tie the piece of brass with a thread and dip it
completely into water.
- The level of water rises. Note the reading of new water
level V2.
The
difference in the two levels of water gives the volume of the piece of brass.
Question 3
Describe the method in steps to find the area of an
irregular lamina using a graph paper.
Answer
To find the area of an irregular lamina using a graph paper.
- Put the lamina on a graph paper.
- Now draw boundary line on the graph paper.
- Remove the lamina.
- Count and note the number of complete squares, half
squares and more than half squares within the boundary line. Ignore the
squares which are less than half.
The sum of the areas of the number of complete squares and
the number of incomplete squares gives the approximate area of the irregular
object.
(D) Numerals Questions Answers:
Numericals
Question 1
The length, breadth and height of a water tank are 5 m, 2.5
m and 1.25 m respectively. Calculate the capacity of the water tank in:
a. m3
b. litre
Answer
Length = 5 m; breadth = 2.5 m; height = 1.25 m
a. Volume of water tank = length x breadth x height = 5 m x
2.5 m x 1.25 m = 15.625 m3
So, capacity of water tank in m3 = 15.625 m3.
b. 1 m3 = 1000 L
15.625 m3 = 15.625 x 1000 = 15625 L
So, capacity of water tank in litres = 15,625 L.
Question 2
A solid silver piece is immersed in water contained in a
measuring cylinder. The level of water rises from 50 mL to 62 mL. Find the
volume of silver piece.
Answer
Initial level of water V1 = 50 mL
Final level of water V2 = 62 mL
Volume of silver piece = V2 - V1
= 62 - 50
= 12 mL = 12 cm3
So, volume of silver piece = 12 cm3.
Question 3
Find the volume of a liquid present in a dish of dimensions
10 cm x 10 cm x 5 cm.
Answer
Volume of dish = 10 cm x 10 cm x 5 cm = 500 cm3.
Volume of liquid is equal to volume of dish = 500 cm3.
1 cm3 = 1 mL
500 cm3 = 500 mL
So, volume of a liquid present in the dish = 500 mL.
Question 4
A rectangular field is of length 60 m and breadth 35 m. Find
the area of the field.
Answer
Length = 60 m
Breadth = 35 m
Area of the field = Length x Breadth = 60 m x 35 m = 2100 m2.
So, the area of the field = 2100 m2.
Question 5
Find the approximate area of an irregular lamina of which the boundary line is drawn on the graph paper shown in the figure below.
Answer
Number of complete squares = 11
Number of more than half squares = 8
Number of half squares = 2
Total number of squares = 11 + 8 + 2 = 21
Area of the square = 1 cm x 1 cm = 1 cm2
Area of 21 squares = 21 x 1 = 21 cm2
So, approximate area of lamina = 21 cm2.
Question 6
A piece of brass of volume 30 cm3 has a mass
of 252 g. Find the density of brass in:
(i) g cm-3
(ii) kg m-3
Answer
Mass = 252 g
Volume = 30 cm-3
Density = ?
(i) Density=Mass/Volume
Density=252/30=8.4g cm−3
So, Density = 8.4 g cm-3.
(ii) 1 g cm-3 = 1000 kg m-3
8.4 g cm-3 = 8.4 x 1000 = 8400 kg m-3
So, Density = 8400 kg m-3.
Question 7
The mass of an iron ball is 312 g. The density of iron is
7.8 g cm-3. Find the volume of the ball.
Answer
Mass = 312 g
Density = 7.8 g cm-3
Volume = ?
Density=Mass/Volume
7.8=312/Volume
Volume=312/7.8=40cm3
So, volume of the ball is 40 cm3.
Question 8
A cork has a volume 25 cm3. The density of cork
is 0.25 g cm-3. Find the mass of the cork.
Answer
Volume = 25 cm3
Density = 0.25 g cm-3
Mass = ?
Density=Mass/Volume
0.25=Mass/25
Mass=0.25×25=6.25g
So, mass of the cork is 6.25 g.
Question 9
The mass of 5 litre of water is 5 kg. Find the density of
water in g cm-3.
Answer
Mass = 5 kg
Volume = 5 litre
Density = ?
Density=Mass/Volume
Density=5/5=1kg litre−1
Density = 1 kg litre-1
1 kg = 1000 g; 1 litre = 1000 cm3
1 kg litre-1 = 1000/1000 =
1 g cm-3
So, density of water = 1 g cm-3.
Question 10
A cubical tank of side 1 m is filled with 800 kg of a
liquid. Find:
(i) the volume of tank
(ii) the density of liquid in kg m-3.
Answer
Side = 1 m; mass = 800 kg
(i) Volume of cubical tank = (side)3 = (1 m)3 =
1 m3
So, the volume of the tank = 1 m3.
(ii) Density=Mass/Volume
Density=800/1=800kg m3
So, density of liquid = 800 kg m-3.
Question 11
A block of iron has dimensions 2 m x 0.5 m x 0.25 m. The
density of iron is 7.8 g cm-3. Find the mass of the block.
Answer
Density of iron = 7.8 g cm-3
1 g cm-3 = 1000 kg m-3
7.8 g cm-3 = 7.8 x 1000 = 7800 kg m-3
Volume of iron = 2 m x 0.5 m x 0.25 m = 0.25 m3
Mass = ?
Density=Mass/Volume
7800=Mass/0.25
Mass=7800×0.25=1950kg
So, mass of iron = 1950 kg.
Question 12
The mass of a lead piece is 115 g. When it is immersed into
a measuring cylinder, the water level rises from 20 mL mark to 30 mL mark.
Find:
(i) the volume of the lead piece,
(ii) the density of the lead in kg m-3.
Answer
(i) Mass = 115 g;
Initial volume V1 = 20 mL;
Final volume V2 = 30 mL;
Volume of lead piece = V2 - V1 = 30 - 20 = 10
mL
1 mL = 1 cm3
10 mL = 10 cm3
So, the volume of the lead piece = 10 cm3.
(ii) Density = ?
Density=Mass/Volume
Density=115/10=11.5g cm3
1 g cm-3 = 1000 kg m-3
11.5 g cm-3 = 1000 x 11.5 = 11500 kg m-3
So, the density of lead = 11500 kg m-3.
Question 13
The density of copper is 8.9 g cm-3. What will be
its density in kg m-3?
Answer
1 g cm-3 = 1000 kg m-3
8.9 g cm-3 = 8.9 x 1000 = 8900 kg m-3
So, density of copper = 8900 kg m-3.
Question 14
A car travels a distance of 15 km in 20 minutes. Find the
speed of the car in:
(i) km h-1
(ii) m s-1
Answer
(i) distance = 15 km; time = 20 min
60 min = 1 hr
20 min = 20/60 = 1/3 h
Speed=distance/time
=15/1/3=15×3=45km h−1
So, speed of car = 45 km h-1.
(ii) distance = 15 km
1 km = 1000 m
15 km = 15 x 1000 = 15000 m
time = 20 min
1 min = 60 sec
20 min = 20 x 60 = 1200 sec
Speed=distance/time
=15000/1200=12.5 m s−1
So, speed of car = 12.5 m s-1.
Question 15
How long a train will take to travel a distance of 200 km
with a speed of 60 km h-1?
Answer
distance = 200 km; speed = 60 km h-1
time = ?
Speed=distance/time
60=200/time time
=200/60=3h 20min
So, time taken by train will be 3 hrs 20 minutes.
Question 16
A boy travels with a speed of 10 m s-1 for
30 minute. How much distance does he travel?
Answer
Speed = 10 m s-1
time = 30 minutes
1 min = 60 sec
30 min = 60 x 30 = 1800 sec
distance = ?
Speed=distance/time
10=distance/1800
distance=1800×10=18000 m
So, distance travelled = 18000 m or 18 km.
Question 17
Express 36 km h-1 in m s-1.
Answer
1 km h-1 = 518185 m s-1
36 km h-1 = 36 x 518185 = 10 m s-1
So, 36 km h-1 = 10 m s-1.
Question 18
Express 15 m s-1 in km h-1.
Answer
1 m s-1 = 3.6 km h-1
15 m s-1 = 3.6 x 15 = 54 km h-1
So, 15 m s-1 = 54 km h-1.
Distance Speed Volume
Time Density SI unit
Lamina Cylinder Beaker
Length Metre Centimetre
Mass CGS unit Flask
Millimetre Kilogram Radius
===============================================
Share,
Like and Comment Please…
No comments:
Post a Comment