Samacheer Kalvi 7th Science Term 1 Solutions Chapter 1 Pdf
Tamilnadu Board Samacheer Kalvi 7th Science Term 1 Solutions Chapter 1: Tamilnadu State Board Solution Class 7 Science Term 1 Chapter 1 – Measurement.
Samacheer Kalvi 7th Science Term 1 Solutions Chapter 1: Overview
Board |
Samacheer Kalvi |
Class |
7 |
Subject |
Science |
Chapter |
1 |
Chapter Name |
Measurement |
Samacheer Kalvi 7th Science Term 1 Solutions Chapter 1 Pdf
Measurement
Chapter 1
I.) Choose the best answer.
1.) Which of the following is a derived quantity?
a) mass
b) time
c) area
d) length
Answer: c) area
Solution: The physical quantities which can be obtained by multiplying, dividing or by mathematically combining the fundamental quantities are known as derived quantities. Eg. Area and volume
2.) Which of the following is correct?
a) 1L = 1cc
b) 1L = 10 cc
c) 1L = 100 cc
d) 1L = 1000 cc
Answer: d) 1L = 1000 cc
Solution: The unit of volume is cubic cm if the dimensions of the object are given in cm. This cubic cm is commonly known as ‘cc’.
A volume of 1000 cc is termed as one litre (l).
1 litre = 1000 cc or cm3
3.) SI unit of density is
a) kg/m2
b) kg/m3
c) kg/m
d) g/m3
Answer: b) kg/m3
Solution: Density of a substance is defined as the mass of the substance contained in unit volume. SI unit of density is kg/m3.The CGS unit of
density is g/cm3.
4.) Two spheres have mass and volume in the ratio 2:1. The ratio of their density is
a) 1:2
b) 2:1
c) 4:1
d) 1:4
Answer: a) 1:2
Solution: d =m/v
m1 = m2
v1/v2 = 2/1
d1/d2= m1×v2/m2×v1
therefore d1/d2= 1/2
5.) Light year is the unit of
a) distance
b) time
c) density
d) Both length and time
Answer: a) distance
Solution: One light year is defined as the distance travelled by light in vacuum during the period of one year. 1 Light year = 9.46 × 1015 m.
II.) Fill in the blanks.
1.) Volume of irregularly shaped objects are measured using the law of Archimedes’ Principle
2.) One cubic metre is equal to 1000000 cubic centimetre.
3.) Density of mercury is 13,600kg/m3
4.) One astronomical unit is equal to 1.496 × 1011 m
5.) The area of a leaf can be measured using a graph sheet.
III.) State true or false, correct the statement.
1.) The region covered by the boundary of a plane figure is called its volume.
Answer: False
Correct Statement: The region covered by the boundary of a plane figure is called its area.
2.) Volume of liquids can be found using measuring containers.
Answer: True
3.) Water is denser than kerosene.
Answer: True
4.) A ball of iron floats in mercury.
Answer: False
Correct Statement: A ball of iron sinks in mercury. Because iron is denser than mercury.
5.) A substance which contains less number of molecules per unit volume is said to be denser.
Answer: False
Correct Statement: A substance which contains more number of molecules per unit volume is said to be denser
IV.) Match the following items.
a.)
1.) Area | c. m2 |
2.) Distance | a. light year |
3.) Density | e. kg / m3 |
4.) Volume | b. m3 |
5.) Mass | d. kg |
b.)
1.) Area | e. plane figures |
2.) Length | d. rope |
3.) Density | a. g / cm3 |
4.) Volume | b. measuring jar |
5.) Mass | c. amount of a substance |
V.) Arrange the following in correct sequence.
1.) 1L, 100 cc, 10 L, 10 cc
Answer : 10L, 1L, 100cc, 10cc
2.) Copper, Aluminium, Gold, Iron
Answer: Aluminum, Iron, copper, Gold
VI.) Use the analogy to fill in the blank.
1.) Area : m2 :: Volume : __m3_______
2.) Liquid : Litre :: Solid : ___kilogram ______
3.) Water : Kerosene :: __Wood_____ : Aluminium
VII.) Consider the following Statements and choose the correct option.
1.) Assertion: Volume of a stone is found using a measuring cylinder.
Reason: Stone is an irregularly shaped object.
Answer: d. Assertion is false but reason is true
2.) Assertion: Wood floats in water.
Reason: Water is a transparent liquid.
Answer: b. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3.) Assertion: Iron ball sinks in water.
Reason: Water is denser than iron.
Answer: c. Assertion is true but reason is false.
VIII.) Answer very briefly.
1.) Name some of the derived quantities.
Answer: Some drived quantities are speed , density , area , electric charge etc.
2.) Give the value of one light year.
Answer: 1 Light year = 9.46 × 1015 m
3.) Write down the formula used to find the volume of a cylinder.
Answer: Volume of Cylinder = π × (radius)2 × height= π r2h.
4.) Give the formula to find the density of objects.
Answer: Density (D) = Mass (M)/Volume (V) = kg/m3
5.) Name the liquid in which iron ball sinks.
Answer: Iron ball sink in water
6.) Name the units used to measure the distance between celestial objects.
Answer: The units used to measure the distance between celestial objects is astronomical unit .
7.) What is the density of gold?
Answer: Gold density = 19,300 kg/m3
IX.) Answer briefly.
1.) What are derived quantities?
Answer: The physical quantities which can be obtained by multiplying, dividing or by mathematically combining the fundamental quantities are known as derived quantities.
2.) Distinguish between the volume of liquid and capacity of a container.
Answer: The amount of space occupied by a three dimensional object is known as its volume. The maximum volume of a liquid that a container can is known as the capacity of the container.
3.) Define the density of objects.
Answer: Density of an object is defined as the mass of the object contained in unit volume(1 m3).
4.) What is one light year?
Answer: One light year is defined as the distance travelled by light in vacuum during the period of one year.
5.) Define – Astronomical unit.
Answer: One astronomical unit is defined as the average distance between the earth and the sun.
X.) Answer in detail.
1.) Describe the graphical method to find the area of an irregularly shaped plane figure.
Answer: First draw the irregular figure whose are we have to find on graph paper with the help of pencil
i) Now , count the number of boxes which are full and inside the figure you have draw . Take it as F
ii) Now, count the number of boxes which are more than half and inside the outline of figure. Take it as M
iii) Now, count the number of boxes which are half and inside the outline of figure. Take it as H
iv) now count the number of boxes which are less than half and inside the outline of figure. Take it as L
Now, the approximate area of the figure can be calculated using the following formula.
Approximate area of the figure
= F + (3/4) M + (1/2) H + (1/4) L square cm.
Area of the figure = ______________cm2.
2.) How will you determine the density of a stone using a measuring jar?
Answer: i) For measuring the density of stone using jar first we will fill the jar with water and put the stone inside it .
ii) As we know , stone will sink in the jar which is filled with water.
iii) Some amount of water will be overflown from the jar now take out the stone from the jar and take the measurements of water that had overflown from the jar by seeing jar’s reading .
iv) That measurements show the density of the stone.
XI.) Questions based on Higher Order Thinking Skills:
i.) Find the ratio of masses of spheres A and B.
Answer: Mass of A : Mass of B
volume of A ×density of A : volume of B ×density of B
[density of A = density of B]
therefore, volume of A :Volume of B
4/3πrA3 :4/3πrB3. (rB=1/2rA)
rA3 : 1/8 rA
8 : 1
ii.) Find the ratio of volumes of spheres A and B.
Answer: volume of A : volume of B
4/3πrA3 :4/3πrB3. (rB=1/2rA)
rA3 : 1/8 rA
8 : 1
iii.) Find the ratio of masses of spheres A and C.
Answer: mass of A : mass of C
volume of A× density of A : volume of C × density of C
radius of A and C is same
therefore, volume of A = volume of C
density of A : density of C
2 density of C : density of C [density of A is equal to double of density of C]
therefore ratio is 2:1
XII.) Numerical problems:
1.) A circular disc has a radius 10 cm. Find the area of the disc in m2 (Use π = 3.14).
Answer: Radius of a disc = 10 cm
10cm= 0.1m
Area of disc = πr2 = 3.14×0.1×0.1 = 0.0314m2
2.) The dimension of a school playground is 800 m × 500 m. Find the area of the ground.
Answer: Length of ground = 800m
Breath of ground = 500m
Area of ground = length ×breadth = 800 ×500= 400000m2 = 4×10*5
3.) Two spheres of same size are made from copper and iron respectively. Find the ratio between their masses (Density of copper is 8,900 kg/m3 and iron is 7,800 kg/m3).
Answer: Volume of Copper Sphere = Volume of iron Sphere
Let, Vcu = VFe
Formula of mass = volume × density
M = V × d
Mass ratio is , Mcu = MFe
Vcu × 8,900 hg/m3 : VFe × 7,800 hg/m3
Vcu × 89 : VFe × 78
89 : 78
Ratio of mass of spheres of Copper and Iron is = 89 : 78.
4.) A liquid having a mass of 250 g fills a space of 1000 cc. Find the density of the liquid.
Answer: Mass of the liquid = 250 g
Volume of the liquid = 1000cc
= 250 g / 1000cc
= 0.25 g/cc
Density of the liquid = 0.25g cc-1
5.) A sphere of radius 1cm is made from silver. If the mass of the sphere is 33g, find the density of silver (Take π = 3.14).
Answer: Radius of the silver sphere = 1cm
Its mass = 33 g
Volume of the sphere = 4/3 πr3
= 4/3 × 3.14 × (1cm)3
= 4/3 × 3.14 × 13 cm3
Density of sphere (d) = Mass / Volume
= (33 / 3.14) × 3/4 × g.cm-3
Density of sphere = 7.88 g/cm3.
XIII.) Cross word puzzle.
Answers:
1.) Kelvin
2.) Volume
3.) Density
4.) Capacity
Answers:
a.) Velocity
b.) Cubic metre
c.) Mercury
d.) Light year