Samacheer Kalvi 8th Science Solutions Term 3 Chapter 3 Universe and Space Science

Tamilnadu Samacheer Kalvi 8th Science Solutions Term 3 Chapter 3 Universe and Space Science

Samacheer Kalvi 8th Science Universe and Space Science Text Book Exercise

 

I. Choose the best answer:

Question 1.
Which of the following is a celestial body?
(a) Sun
(b) Moon
(c)Stars
(d) All the above
Answer:
(d) All the above

Question 2.
Mangalyaan was sent to …………….
(a) Moon
(b) Mars
(c) Venus
(d) Mercury
Answer:
(b) Mars

 

Question 3.
Chandrayaan -1 was launched on …………….
(a) 22nd October 2008
(b) 8th November 2008
(c) 22nd July 2019
(d) 22nd October 2019
Answer:
(a) 22nd October 2008

Question 4.
……………. is called as Red planet.
(a) Mercury
(b) Venus
(c) Earth
(d) Mars
Answer:
(d) Mars

 

Question 5.
Which of the following is the working principle of Rockets?
(a) Newton’s first law
(b) Newton’s second law
(c) Newton’s third law
(d) All the above
Answer:
(c) Newton’s third law

Question 6.
Cryogenic fuels are stored at …………….
(a) room temperature
(b) low temperature
(c) very low temperature
(d) very high temperature
Answer:
(c) very low temperature

 

Question 7.
……………. was the first manned mission of NASA to go to the moon.
(a) Apollo-5
(b) Apollo-8
(c) Apollo-10
(d) Apollo-11
Answer:
(b) Apollo-8

II. Fill in the blanks:

1. The study about stars and planets are known as ……………
2. Our Sun belongs to …………… Galaxy.
3. Mars revolves around the Sun once in …………… days.
4. …………… is India’s first interplanetary mission.
5. …………… was the first man to walk on the surface of the Moon.

Answer:

1. Astronomy
2. Milky way
3. 687
4. Mars Orbiter Mission
5. Neil Armstrong

III. Say True or False. If false, correct the statement:

Question 1.
The Sun and the celestial bodies form Solar system.
Answer:
true

Question 2.
Chandrayaan-1 was launched from Sriharikota.
Answer:
True.

 

Question 3
Mars is the smallest planet in the Solar system.
Answer:
False
Correct statement:
Mercury is the smallest planet in the Solar system.

Question 4.
PSLV and GSLV are India’s popular satellites.
Answer:
True.

Question 5.
The propellant of a rocket is only in the form of solids.
Answer:
False Correct statement:
The propellant of a rocket is may be in the form of solids or liquids.

 

IV. Match the following:

1. Chandrayaan – Fuel
2. Mangalyaan – Moon
3. Cryogenic – First manned mission to the moon
4. Apple – 8 – First man landing mission to the moon
5. Apollo-11 – Mars

Answer:

1. Chandrayaan – Moon
2. Mangalyaan – Mars
3. Cryogenic – Fuel
4. Apple – 8 – First manned mission to the moon
5. Apollo-11 – First man landing mission to the moon

V. Answer briefly:

Question 1.
What are celestial objects?
Answer:
The stars, the planets, the Moon and any other objects like asteroids and comets in the sky are called celestial objects.

Question 2.
Define galaxy.
Answer:
A collection of billions of stars held together by mutual attraction is called galaxy.

 

Question 3.
What are the objectives of Chandrayaan-1?
Answer:

1. To find the possibility of water on the Moon.
2. To find the elements of matter on the Moon.
3. To search for the existence of Helium-3.
4. To make a 3-dimensional atlas of the Moon.
5. To study about the evolution of the solar system.

Question 4.
List out the objectives of Mangalyaan.
Answer:

1. To develop the technology required for interplanetary mission. .
2. To explore the surface of Mars.
3. To study the constituents of the Martian atmosphere.
4. To provide information about the future possibility of life and past existence of life

 

Question 5.
What are Cryogenic Fuels?
Answer:
Cryogenic fuels are the fuels used in rocket engine. They are maintained or stored at very low temperature in order to keep them in liquid state.

Question 6.
Name the Indians worked at NASA.
Answer:
Kalpana Chawla and Sunitha Williams.

 

VI. Answer in detail:

Question 1.
What are the achievements of Chandrayaan -1?
Answer:

1. The discovery of presence of water molecules in the lunar soil.
2. Chandrayaan-1 confirmed that the Moon was completely molten once.
3. Chandrayaan-1 has recorded images of the landing site of the US space-craft Apollo-15 and Apollo-11.
4. It has provided high-resolution spectral data on the mineralogy of the Moon.
5. The existence of aluminium, magnesium and silicon were picked up by the X-ray camera.
6. More than 40,000 images have been transmitted by the Chandrayaan-1 camera in 75 days.
7. The acquired images of peaks and craters show that the Moon mostly consists of craters.
8. Chandrayaan-1 beamed back its first images of the Earth in its entirety.
9. Chandrayaan-1 has discovered large caves on the lunar surface that can act as human shelter on the Moon.

 

Question 2.
Explain the parts of a rocket.
Answer:
There are four major parts or systems in a rocket. They are:

1. Structural system
2. Payload system.
3. Guidance system.
4. Propulsion system.

1. Structural system (Frame):
It is the frame that covers the rocket. It is made up of very strong but light weight materials like titanium or aluminum. Fins are attached to some rockets at the bottom of the frame to provide stability during the flight.

2. Payload system:
It is the object that the satellite is carrying into the orbit. Payload depends on the rocket’s mission. The rockets are modified to launch satellites with a wide range of missions like communications, weather monitoring, spying, planetary exploration, and as observatories. Special rockets are also developed to launch people into the Earth’s orbit and onto the surface of the Moon.

3. Guidance system:
Guidance system guides the rocket in its path. It may include sensors, on-board computers, radars, and communication equipments.

4. Propulsion system:
It takes up most of the space in a rocket. It consists of fuel (propellant) tanks, pumps and a combustion chamber. There are two main types of propulsion systems. They are: liquid propulsion system and solid propulsion system.

 

Question 3.
Write a note on Apollo missions.
Answer:

1. Apollo Missions are the most popular missions of NASA.
2. These missions made American Astronauts to land on the Moon.
3. It consists of totally 17 missions.
4. Among them Apollo -8 and Apollo-11 are more remarkable.
5. Apollo-8 was the first manned mission to go to the Moon. It orbited around the Moon and came back to the Earth.
6. Apollo-11 was the first ‘Man Landing Mission’ to the moon. It landed on the Moon on 20th July 1969. –
7. Neil Armstrong was the first man to walk on the surface of the Moon.

VII. Higher Order Thinking Questions:

Question 1.
Why we are always seeing one side of the Moon?
Answer:
Moon doesn’t have its own light, but it reflects the sunlight. The time period of rotation of the Moon about its own axis is equal to the time period of revolution around the Earth. That’s why we are always seeing its one side.

Samacheer Kalvi 8th Science 3 Universe and Space Science Additional Questions

I. Choose the correct answer:

Question 1.
……………. was the first man landing mission to go to the Moon.
(a) Apollo 8
(b) Apollo 11
(c) Chandrayaan – 1
(d) Chandrayaan – 2
Answer:
(b) Apollo 11

 

Question 2.
……………. is India is first interplanetary mission.
(a) MOM
(b) Mangalyaan
(c) Chandrayaan -1
(d) None
Answer:
(b) Mangalyaan

Question 3.
……………. system guides the rocket in its path.
Answer:
(a) Propulsion
(b) Structural
(c) Payload
(d) Guidance
Answer:
(d) Guidance

 

Question 4.
Liquid hydrogen, hydrazine and ……………. are the liquid fuels.
Answer:
(a) Methyl alcohol
(b) Nitrate
(c) Chlorate salts
(d) Ethyl alcohol
Answer:
(d) Ethyl alcohol

Question 5.
To provide information about the future possibility of life and past existence of life on the planet. This is one the objectives of …………….
Answer:
(a) Chandrayaan – 1
(b) Chandrayaan – 2
(c) Mangalyaan
(d) Apollo 8
Answer:
(c) Mangalyaan

 

II. Fill in the blanks:

1. The Sun and the Celestial bodies revolving around it form the ……………
2. A collection of billions of stars held together by mutual attraction is called ……………
3. Our Sun belongs to a galaxy called ……………
4. Billions of galaxies form the ……………
5. The …………… system is the frame that covers the rocket.
6. …………… and …………… rockets are India’s popular rockets.
7. The first ever satellite …………… was launched in 1975.
8. Mars rotates about its own axis once in …………… hours …………… minutes.
9. …………… became the first Asian country to reach Mars and the first nation in the world to achieve this in the first attempt.
10. …………… became the first Indian women astronaut to go to space.

Answer:

1. solar system
2. galaxy
3. Milky way
4. Universe
5. structural
6. PSLV, GSLV
7. Aryabhata
8. 24, 37
9. India
10. Kalpana Chawla

 

III. True or False – if false, give the correct statement:

Question 1.
Propulsion system may include sensors, radars and communication equipments.
Answer:
False

Correct statement:
Guidance system may include sensors, radars and communication equipments.

Question 2.
Structural system is made up of very strong but light weight materials like titanium and aluminium.
Answer:
True.

 

Question 3.
The propellants may be in the form of a liquid or gas.
Answer:
False

Correct statement:
The propellants may be in the form of a liquid or solid.

Question 4.
Liquid hydrogen, hydrazine and ethyl alcohol are the liquid fuels.
Answer:
True.

Question 5.
Combustion of solid propellants can be stopped once it is ignited.
Answer:
False

Correct statement:
Combustion of solid propellants cannot be stopped once it is ignited.

 

IV. Match the following:

1. Chandrayaan – 1 – (a) Cosmonaut
2. Chandrayaan – 2 – (b) Mars Orbiter
3. Mangalyaan – (c) Dr. Mylsamy Annadurai
4. Rakesh Sharma – (d) Dr. Kailasa vadivoo Sivan

Answer:

1. c
2. d
3. b
4. a

V. Very short answer questions:

Question 1.
Name an Indian pilot who was selected as a cosmonaut in a joint space program between India and Soviet Russia.
Answer:
Rakesh Sharma.

 

Question 2.
Name the solid fuels used in rockets.
Answer:
Polyurethanes and Polybutadienes.

Question 3.
Name the fuels which do not need any ignition system.
Answer:
Cryogenic fuels.

Question 4.
Name the principle which is used in rocket propulsion.
Answer:
Newton’s third law (For every action there is an equal and opposite reaction).

Question 5.
What are the 4 major parts or systems in a rocket?
Answer:

1. Structural system
2. Payload system
3. Guidance system
4. Propulsion system

Question 6.
Name the 2 popular rockets of India.
Answer:
Polar satellite launch vehicle (PSLV). Geosynchronous satellite launch vehicle (GSLV)

 

Question 7.
What are the most popular missions of NASA?
Answer:
Apollo missions

VI. Short answer questions:

Question 1.
Write a note on propulsion system of rocket.
Answer:

1. It takes up most of the space in a rocket.
2. It consists of fuel (propellant) tanks, pumps and a combustion chamber.
3. There are two main types of propulsion systems, liquid propulsion system and solid propulsion system.

 

Question 2.
What is a propellant?
Answer:
A propellant is a chemical substance that can undergo combustion to produce pressurized gases whose energy is utilized to move a rocket against the gravitational force of attraction.

Question 3.
Write a note on orbiter and lander of Chandrayaan – 2.
Answer:
1. Orbiter:
It revolves around the Moon and it is capable of communicating with Indian Deep Space Network (IDSN) at Bylalu as well as Vikram Lander.

2. Lander:
It is named as Vikram in the memory of Dr. Vikram A. Sarabhai, the father of Indian space program

 

Question 4.
Write about Sunitha William’s work at NASA.
Answer:

1. Sunitha Williams started her career as an astronaut in August 1998.
2. She made two trips to the International Space Station.
3. She set a record of the longest space walking time by a female astronaut in 2012, with a total space walk of 50 hour and 40 minute (7 space walks).
4. She is one of the crew of NASA’s Manned Mars Mission.

VII. Long answer questions:

Question 1.
Explain about the launching of satellite in a particular orbit.
Answer:

1. Before being launched into the space, rockets will be held down by the clamps on the launching pad initially.
2. Manned or unmanned satellites will be placed at the top of the rocket.
3. When the fuel in the rocket is burnt, it will produce an upward thrust. There will be a point at which the upward thrust will be greater than the weight of the satellite.
4. At that point, the clamp will be removed by remote control and the rocket will move upwards.
5. According to Newton’s third law, for every action there is an equal and opposite reaction.
6. As the gas is released downward, the rocket will move upward.
7. To place a satellite in a particular orbit, a satellite must be raised to the desired height and given the correct speed and direction by the launching rocket.
8. If this high velocity is given to the rocket at the surface of the Earth, the rocket will be burnt due to air friction.
9. Moreover, such high velocities cannot be developed by a single rocket, So. multistage rockets are used.

 

Question 2.
Explain the two types of propellant.
Answer:
1. Liquid propellants:

• Fuel and oxidisers are combined in a combustion chamber where they bum and come out from the base of the rocket with a great force.
• Liquid hydrogen, hydrazine and ethyl alcohol are the liquid fuels.
• Some of the oxidizers are oxygen, ozone, hydrogen peroxide and fuming nitric acid.

2. Solid propellants :

• Fuel and oxidiser compounds are already combined.
• When they are ignited they bum and produce heat energy.
• Combustion of solid propellants cannot be stopped once it is ignited.
• Solid fuels used in rockets are polyurethanes and polybutadienes. Nitrate and chlorate salts are used as oxidizers.