AP 8th Class Physics 11th Lesson Questions and Answers Stars and the Solar System

AP State Board new syllabus 8th Class Physics Guide 11th Lesson Stars and the Solar System Textbook Exercise Questions and Answers.

AP 8th Class Physical Science 11th Lesson Questions and Answers Stars and the Solar System

8th Class Physics 11th Lesson Stars and the Solar System Questions and Answers (Exercise)

Choose the correct answer in Questions 1-3.

Question 1.
Which of the following is NOT a member of the solar system ?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet
Answer:
(c) A constellation

Question 2.
Which of the following is NOT a planet of the sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth
Answer:
(a) Sirius

Question 3.
Phases of the moon occur because
(a) we can see only that part of the moon which reflects light towards us.
(b) our distance from the moon keeps changing.
(c) the shadow of the Earth covers only a part of the moon’s surface.
(d) the thickness of the moon’s atmosphere is not constant.
Answer:
(a) we can see only that part of the moon which reflects light towards us.

Question 4.
Fill in the blanks.
a) The planet which is farthest from the Sun is …………
b) The planet which appears reddish in colour is …………
c) A group of stars that appear to form a pattern in the sky is known as a …………
d) A celestial body that revolves around a planet is known as …………
e) Shooting stars are actually not …………
f) Asteroids are found between the orbits of ………… and …………
Answer:
a) Neptune
b) Mars
c) Constellation
d) Satellite
e) Meteors
f) Mars and Jupiter

Question 5.
Mark the following statements as true (T) or false (F).
(a) Pole star is a member of the solar system.
Answer: False

(b) Mercury is the smallest planet of the solar system.
Answer: True

(c) Uranus is the farthest planet in the solar system.
Answer: False

(d) INSAT is an artificial satellite.
Answer: True

(e) There are nine planets in the solar system.
Answer: False

(f) Constellation Orion can be seen only with a telescope.
Answer: False

Question 6.
Match items in column A with one or more items in column B.
Answer:

A	B
i) Innti planets	a) Saturn
ii) Outer planets	b) Pole star
iii) Constellation	c) Great Bear
iv) Satellite if the Earth	d) Moon
	e) Earth
	f) Orion
	g) Mars

Question 7.
In which part of the sky can you find Venus if it is visible as an evening star?
Answer:
In western part of the sky we can find Venus is visible as an evening star.

Question 8.
Name the largest planet of the solar system.
Answer:
Jupiter is the largest planet of the solar system.

Question 9.
What is a constellation? Name any two constellations.
Answer:
Constellations are groups of stars that appear to form recognisable shapes.
Examples : Orion, Cassiopeia and Ursa Major.

Question 10.
Draw sketches to show the relative positions of prominent stars in
(a) Ursa Major and
(b) Orion

Question 11.
Name two objects other than planets which are members of the solar system.
Answer:

• The moon
• Asteroids
• Halley’s Comet are the members of the solar system.

Question 12.
Explain how you can locate the Pole Star with the help of Ursa Major.
Answer:

• Look at the sky on a clear moonless night during summer at about 9:00 pm.
• Look towards the northern part of the sky and identify Ursa Major.
• Look at the two stars at the end of Ursa Major.
• Imagine a straight line passing through these stars.
• Extend this imaginary line towards the north direction. (About five times the distance between the two stars.)
• This line will lead to a star which is not too bright.
• This is the Pole star.
• Observe the Pole star for some time.
• Note that it does not move at all as other stars drift from east to west.

Question 13.
Do all the stars in the sky move? Explain.
Answer:
Yes. All the stars in the sky move except pole star.
(Note : Actually, all the stars, including revolve around the respective galaxies.)

Question 14.
Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?
Answer:

• We cannot read the larger distance between the stars in kilometres conveniently.
• Some stars are even further away.
• For example : The next nearest star is Proxima Centauri is at a distance of about 40,000,000,000,000 km from the Earth.
• It is difficult to read.
• Such large distances are expressed in the unit known as light year.
• Light year is the distance travelled by light in one year.
• A star is eight light years away from the Earth means the total distance travel by the light in 8 years. That means 75685843780646 km.

Question 15.
The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accomodate?
Answer:
Let the radius of Earth = R units
Volume of Earth = \(\frac{4}{3}\) × R³ cubic units

So, 1331 Earths can be accomnodated in one Jupiter.

Question 16.
Boojho made the following sketch of the solar system. Is the sketch correct? If not, correct it.
Answer:

A. Boojho’s sketch of the solar system is not correct because he has interchanged the positions of Mars and Venus and also the positions of Uranus and Neptune. Also, he has shown the Asteroid belt in the gap between the orbits of Jupiter and Saturn. This is not correct. The asteroid belt is located between the orbits of Mars and Jupiter.

Extended Learning – Activities and Projects

Question 1.
The North-South line at your place.
Let us learn to draw the north-south line with the help of the shadow of a stick. Fix a straight stick vertically in the ground where the Sun can be seen for most of the day. Call the foot of the stick as point O. Sometime in the morning, mark the tip of the shadow of the stick. Say this point is A . With OA as radius draw a circle on the ground. Wait till the shadow becomes shorter and then starts increasing in size. When the shadow again touches the circle, mark it as point B. Draw the bisector of the angle AOB. This is your North-South line. To decide which side of this line shows North, use a magnetic compass.
Answer:
Do it yourself.

Question 2.
If possible, visit a planetarium. There are planetariums in many cities. In a planetarium, you can see the motion of the stars, constellations and planets on a large dome.
Answer:
Do it yourself.

Question 3.
On a moonless night observe the sky for a few hours. Look out for a meteor, which appears as a streak of light. September-November is a good time for observing meteors.
Answer:
Do it yourself.

Question 4.
Learn to identify the planets visible to the naked eye and some prominent constellations such as Great Bear (Saptarshi) and Orion. Also try to locate the Pole Star and the star Sirius.
Answer:
Do it yourself.

Question 5.
Position of the rising Sun – Uttarayan and Dakshinayan : This activity may last for several weeks. Choose a place from where eastern horizon is clearly visible. Choose also a marker, such as a tree or an electric pole, to mark the position of the rising Sun. It will be sufficient if you take the observation once every week. On any day, note down the direction of the rising Sun. Repeat this observation every week. What do you find? You would have noted that the point of sunrise changes continuously. From summer solstice (around 21 June), the point of sunrise gradually shifts towards the south. The Sun is then said to be in dakshinayan (moving south). It keeps doing so till winter solstice (around 22 December). There after, the point of sunrise changes direction and starts moving towards north. The Sun is now said to be in uttarayan (moving north). From the equator, only on two days, on the days of the equinoxes (around 21 March and 23 September) the Sun rises in the east. On all other days, it rises either north of east or south of east. So, the direction of the rising Sun is not a good guide to determine directions. The Pole Star, which defines North, is a much better indicator of directions.
Answer:
Do it yourself.

Question 6.
Form a group of students. Prepare a model of the solar system showing the planets, and their relative sizes. For this take a large chart paper. Make spheres representing different planets according to their relative size (Use Table). You may use newspaper, clay or plasticine to make spheres. You can cover these spheres with paper of different colours. Exhibit your models in the class.
Answer:

Name of planet	Approximate radius (assuming Earth as 1 unit)	Approximate distance from the Sun (assuming) distance of the Earth as 1 unit)	Period of revolution	Period of rotation
Mercury	0.40	0.39	88 days	59 days
Venus	0.95	0.72	225 days	243 days
Earth	1.00	1.00	365.25 days	24 hours
Mars	0.55	1.50	687 days	24 hours 37 min
Jupiter	11.00	5.20	12 years	9 hours 55 min
Saturn	9.00	9.50	29.46 years	10.66 hours
Uranus	;4.00	19.20	84 years	17.2 hours
Neptune	3.90	30.00	165 years	16.1 hours

Do it yourself.

Question 7.
Try to make a scale model of the solar system showing distances of the planets from the Sun (Use above Table). Did you face any difficulty? Explain it.
Answer:
Difficulty faced while drawing:

• The inner planets are very close to the sun compared to the Uranus and Neptune. So it is difficult to mark the inner planets in scale.
• So, Mercury, Venus, Earth and Mars are marked as very closed dots.

Question 8.
Solve the following riddle and try to make similar riddles yourself :
My first is in VAN but not in PAN
My second is in EARTH and also in HEAVEN
My third is in ONE and not in TWO
My fourth is in BUN and also in FUN
My last is in STAR but not in RADAR
I am a planet that moves round the Sun
Answer:
VENUS
My first is in EAR but not in CAR
My second is in ANT and also in RAT
My third is in RUN and not BUN

My fourth is in COAT and also in JUTE
My last is in HEN but not in TEN
I am a planet that moves around the Sun
I am friend to the Human.
Answer:
EARTH

8th Class PS 11th Lesson Questions and Answers (Lab Activities)

Activity – 1

Observe the moon continuously for several nights, preferably from one full moon to the next. Make a sketch of the moon every night in your note book and note the day from the day of the full moon. Also note everyday the part of the sky (east or west) in which the moon is seen.
Answer:
Do your own (student activity).

Activity – 2

How do you perform an activity to show that the moon appears different at different positions in its orbit?
Answer:

• Take a big ball or a pitcher. Paint half of it white and half black.
• Go out into the playground with two of your friends.
• Draw a circle of radius of about 2m on the ground.

• Divide the circle into eight equal parts as shown in Figure.
• Stand at the centre of the circle.
• Ask a friend to hold the ball at different points of the circle.
• Ask her to keep the white portion of the ball always towards the Sun.
• If you are performing this activity in the morning then the white portion of the ball should be kept towards the east.
• If the activity is being performed in the afternoon then the white portion of the ball should be kept towards the west.
• In each case the line dividing the white and black portions is kept vertical.
• Standing at the centre of the circle observe the visible white portion of the ball while your friend stands at the points on the circle marked earlier.
• Draw the shape of the white portion as you see it.
• Compare your drawings with the different phases of the moon.

Conclusion : The size of the illuminated part of the moon visible from the Earth increases each day after the new moon day. After the full moon day, the sunlit part of the moon visible from the Earth decreases in size every day.

Activity – 3

How do you show that the moon completes one rotation on its axis as it completes one revolution around the Earth ?
Answer:

• Draw a circle of about in diameter on the ground.
• Ask one of your friends to stand at the centre of this circle.
• You revolve around your friend in such a manner that your face always remains towards him.
• Your friend cannot see your back.
• The moon revolves around the Earth in a șimilar manner.

Activity – 4

If the stars appear to move from east to west, it means that the Earth, rotates from west to east. How can you prove it with an activity in your room?
Answer:

• Stand in the centre of a big room and start rotating.
• You can observe that the objects in the room appear to move in the opposite direction of you.
• In the same way we can say that the stars appear to move from east to west. It means that the Earth, rotates from west to east.

Activity – 5

How can you explain the stationary (fixed) position of the pole star? (Activity-5)
Answer:

• Take an umbrella and open it.
• Make about 10 – 15 stars out of white paper.
• Paste one star at the position of the central rod of the umbrella and others at different places on the cloth near the end of each spoke.

• Now rotate the umbrella by holding its central rod in your hand. Observe the stars on the umbrella.
• There is a star that does not appear to move. It is located on the axis of the earth.
• It is the pole star, which is situated in the direction of the earth’s axis. It does not appear to move.

Activity- 6

Does the constellation Ursa Major appear to move in the sky from east to west ?
Answer:

• Observe ursa major constellation for a few hours.
• You will observe that the shape of the constellation remains the same.
• You will also find that the constellation appears to move in the sky from east to west.

Activity – 7

How can you locate the pole star in the sky ?
Answer:

• Look towards the northern part of the sky at night and identify Ursa Major.
• Look at the two stars at the end of Ursa Major.
• Imagine a straight line passing through these stars.
• Extend this imaginary line in the north direction.

(About five times the distance between the two stars.)

• This line will lead to a star which is not too bright.
• This is the Pole star.
• Observe the Pole star for some time.
• Note that it does not move at all as other stars drift from east to west.

Activity – 8

How do you confirm that the Ursa Major rotates around the pole star?
Answer:

• During a summer night, observe ursa Major 3-4 times at an interval of 2 to 3 hours.
• Also locate the Pole star each time.
• You can observe that the Ursa Major appear to move from east to west
• It appears to revolve around the Pole star.

Activity – 9

Do the planets colloids while revolving in their orbits? Prove this with an activity.
Answer:

• Go out into the playground with four or five of your friends.
• Draw four circles of radii 1m, 1.8m, 2.5m and 3.8 m , all having a common centre.
• Ask one of your friends to stand in the centre and represent the Sun.
• Your other four friends may represent Mercury, Venus, Earth and Mars.
• Ask your friends to move around the sun in anti-clockwise direction in their own orbits.
• They do not collide with one another.
• In the same way planets also do not colloid each other while revolving in their orbits.

Activity – 10

Find out from some newspaper or from an almanac the time when Venus is visible in the sky. You can easily recognise Venus by its brightness. Remember that Venus cannot be seen very high in the sky. You must try to observe Venus either 1-3 hours before sunrise or 1-3 hours after sunset.
Answer:
Student Activity.