Download Std 8 PHYSICS 1-Describing Motion Q I Choose the right answer 1

Std 8th PHYSICS
1-Describing Motion
Q I Choose the right answer
1. Uniform circular motion is called continuously accelerated motion mainly because --------direction of motion changes.
2. A cricketer hits a sixer. The cricket ball moves up with a velocity of 2 ms-1
And falls down . Its initial velocity while falling down will be
I Fill in the Blanks
1. S.I unit of acceleration is metre per second square [ms-2 ]
2. Velocity has both speed and direction.
3. If an object starts from ‘A’ and comes back to ‘ A’its displacement will be zero
II solve
1. An Object is moving in a circular path of radius 3.5 m. If it completes one full cycle.
what will be the displacement and what is the distance travelled?
Ans: There is no displacement because the body reaches the same point from where it started
.Hence displacement is zero.
Distance travelled is equal to the circumference of the circular path
B ) Distance travelled by an object=Circumference of the path=2 ∏ r
2 x 22 x 3.5
7
=2 x 22 x 0.5
=22cm is the distance travel
2. An object changes its velocity from 30ms-1 to 40ms-1 in a time interval of 2 second. what
is its acceleration
Ans:U=30ms-1
V=40ms-1 t=2second
Acceleration= Rate of change of velocity
=
Change of velocity
time
=
40 – 30
2
=10
=5 ms-2
2
3. A object at rest starts moving. It covers a distance of 3m in one second. It comes a further
distance of 3m in two second in the same direction. what is its average velocity and acceleration.
Ans: Average velocity=Total distance
= 2+5 =7
= 2 1
ms-1
time
1+2 3
3
Acceleration is to be calculated in 2 stages by using the equation V = u + at
Where V is the final velocity and u’ is the initial velocity. ‘a’ acceleration and t is time
u= o
v = 2/1= 2 , t= 1
V= u + at
2=0+ax1
a = 2 ms-2
II stage u=2 since the final velocity of stage I is the initial velocity at stage II
a=5
u = 2 m/s
t=2
s= ut + ½ at2
5= 2 x 2 + ½ a x 22
5= 4 + ½ a x 4
5 – 4 =2 a
. . . a =1/2
A = 0.5 m / s2
II Answer the following
1) In a body is moving with uniform velocity in a given direction its acceleration will be
zero why?
Ans: There is no change in velocity in the case of uniform velocity therefore acceleration is
zero.
2) Distingiush between speed the velocity.
Speed
Speed is total distance
travelled by an object
in unit time
Velocity
Velocity is
displacement of the
object in unit time.
i.e speed= Distance covered /travelled
Velocity = displacement
time
3.
time
Distingiush between distance travelled and displacement.
Ans: If an object covers a particular distance without the reference of direction is called distance
travelled.
If an object covers a distance in a particular direction it is called displacement.
3) what are uniform and non uniform motions?
Ans: If an object covers equal distance in equal interval of time , it is uniform motion
If an object covers unequal distance in equal intervals of time motion it is non uniform
motion.
4) while mentioning acceleration the time is mentioned two times why?
Ans: Velocity = displacement
time
Acceleration = velocity
Time
= displacement
time
Time
= displacement
A=V =d = d
2
time
t
t
t2
t
Hence acceleration has two times time or time2
FORCE AND NEWTON’S LAWS OF MOTION
Textual Questions and Answers
I. Four alternatives are given to each of the following
statement / question. Chose the right answer.
incomplete
1. Action and reaction
a) act on the same body
b) are equal
c) are opposite
d) act on different bodies
(d)
2. If the forces acting on an object are balanced then
a) the object will be accelerated
b) the object will be in motion
c) the object will have zero acceleration
d) the object loses its shape
(c)
3. The S.I. unit of force is
a) newtons
b) newton
c) newtons
d) newton
(b)
II. Fill in the blanks with suitable words :
1. Inertia of an object is proportional to its ____(Mass)
2. The S.I. unit of momentum is _____(kgms-1)
3. To cause acceleration in an object the necessary factor is unbalanced
_____(force)
4. Newton’s first law of motion is also called law of ____
(inertia)
5. The suitcases kept in moving bus, move forward when
the
applied suddenly this is due to
brakes
are
____(inertia)
III. Answer the following :
1. In a tug of war game two teams exert forces none of the
teams wins why?
Ans : In a tug of war game two teams exert forces opposite
these two forces are equal, according
the rope in the
to each other. If
to Newton’s third law, the point on
middle does not move. Therefore non of the teams
wins.
2. Which of the following has greater momentum?
a) An object of mass 2kg moving with uniform velocity
of 2ms-1
b) An object of 1kg mass moving with uniform velocity
3ms-1
Ans : Momentum = Mass x Velocity
a) Momentum of 2kg mass
= 2x2 =4kgms-1
b) Momentum of 1kg mass
= 1x3 = 3kgms-1
∴ Momentum of 2kg is greater than momentum of
1kg.
3. Which of the following has greater inertia
a) 50 paise coin
b) one rupee coin c) 5 rupee coin
Ans: 5 rupee coin has greater inertia than that of the other
mass is greater than of 50 paise coin
two, because its
and one rupee coin.
4. State any two illustrations for Newton’s third law of motion.
Ans : 1. Strike a ball against the floor, it jumps upward
to action and reaction.
due
2. We are standing on the floor because the floor
a reaction force against our weight.
exerts
5. Distinguish between balanced and unbalanced forces.
Ans : Two equal forces acting opposite to each other are
forces.
6. State Newton’s second law of motion, in terms of
momentum.
Ans : Rate of change of momentum is directly proportional
force and takes place in the
balanced
to the impressed
direction of the application of the
force.
IV. Give reasons for the following :
1. It is dangerous to get down from a moving bus even if
slowly.
the
bus
moving
Ans : When a person is inside the bus he has the inertia as that of the bus. But
when he steps down from the bus and stops on the ground his feet loses his
inertia with respect to the bus, hence he will stumble over to the ground and
will get injury.
2. An athlete in long jump, runs a distance before taking
Ans : An athlete runs a distance before taking the leap to
enough momentum to jump.
3. Usually, a fielder in a cricket match, takes a catch by
in the direction of the motion of
the leap.
attain
moving his hands
cricket ball.
Ans : Cricket ball is moving with a particular inertia and
cricketer
must stretch his hands with same inertia
in the direction of the ball to
get the catch.
V. Solve the problems :
1. Calculate the force required to change the veocity of an
kg from 4ms-1 to 6ms-1 in 2 second.
object of mass 8
Ans : mass = 8kg
Initial Velocity = 4ms-1
Final velocity = 6ms-1
∴ Acceleration =
6−4
2
=
2
2
= 1ms-2
∴F = m a
= 8x1 = 8 Newton
Alternate method using momentum
According to Newton’s second law
F=
𝑚𝑣 −𝑚𝑢
𝑡
u = 4ms-1
v= 6ms-1
t = 2 second
∴F =
=
8𝑥6−8𝑥4
2
48−32
2
=
16
2
= 8 𝑁𝑒𝑤𝑡𝑜𝑛
2. A force of 25 Newton is applied on an object of mass
a velocity of 5ms-1. If the object
gains a velocity of 10ms-1, calculate the
time interval.
Ans : F = 25 newton, u= 5ms-1 v = 10ms-1
M = 10kg
According to Newton’s second law
F=
𝑚𝑣 −𝑚𝑢
25 =
𝑡
10𝑥10−10𝑥5
𝑡
25t = 100-50 = 50
t=
50
25
= 2 second
10kg moving with
∴ time interval is 2 seconds
Alternative method
a=
𝑣−𝑢
𝑡
=
10−5
𝑡
=
5
𝑡
F= ma
25 = 10x
5
𝑡
25t=50
50
t=25 =2 second
3-Energy and Its Forms
I Fill in the blanks
1. Unit of power is watt.
2. Unit of energy is Joule.
3. If a candle is burnt, the chemical energy is transformed into heat and light
4. The water stored in an overhead tank possesses potentional energy.
5. In a cinema theatre electrical energy is transformed into light and sound energy.
II Four alternatives are given choose the right answer.:
1) The type of energy that can be easily converted into other forms is
a)Sound
b)light
c)heat
d)electricity
2) Kinetic energy is present in the following:
a)water stored in a dam.
b)stretched rubber band.
c)water relased from a dam.
d)compressed spring
3)The correct formula to find the velocity of a body with kenetic energy ‘K’ is
a) V=2K/m
b) V= √2K/m
c) V=4k2/m
d) V=1/2m
4) The correct sequence of energy changes in hydroelectric power station is
a) Kinetic to potential, to mechanical to electrical
b) Potentialkineticmechanicalelectrical
c) Potential electricalmechanical
d) potential  electricalkineticmechanical
5)which of the following object has high potential energy?
a) m=10kg,g=9.8ms-1,h=10m
b) m=5kg,g=9.8ms-2,h=10m
 c) m=8kf, g=9.8ms-2,h=10m
d) m=6kg,g=9.8ms-1,h=10m
III answer the following
1) state whether the energy possessed in the following is kinetic a potential.
a) Compressed springpotential energy
b) Stretched lowpotential energy
c) Moving arrowkinetic energy
d) Water stored in dam potential energy
e) A stone at the top of a buildingpotential energy
f) Bird resting on the treepotential energy
2) Distinguish between potential energy and kinetic energy.
Kinetic energy
Potential energy
i)The energy that the body possesses due to
i)The energy which a body posses either due
its motion is called kinetic energy
to its position or due to its deformation is
called potential energy.
ii) Kinetic energy depends upon mass of the ii) Potential energy depends upon mass of
body and velocity.
the body, acceleration due to gravity and
height of the body from the ground.
3) A bus and a car are moving at the same speed. Which of the two has a greater kinetic
energy?
Ans: Bus has got more kinetic energy than that of car because mass of the bus is more than mass
of car.
1) A ball of mass 200gram falls from a height of 5 metre? what is its kinetic energy when it
just reaches the ground?(g=9.8ms-2)
g = 9.8 ms-2
u =0 h(s)= 5m
m= 200g = 1/5
v2 = u2+2gs
= 02 + 2 X 9.8 X 5
= 98ms-1
Kinetic energy = ½ mv2
= ½ X 1/5 X 98 = 9.8 J
so K.E=9.8 J
Ans:
5) There are a number of devices in common use that change energy from one form to
another.name some devices that change
1. Electrical energy into light energy
2. Electrical energy into mechanical energy
3. Electrical energy into heat energy.
4. Sound in electrical
5. Chemical energy into electrical
Ans: 1. Electrical energy into light energy----electric bulb, fluorescent light etc
2. Electrical energy into mechanical energy---electric pump, electric fan etc
3. Electrical energy into heat energy.-----electric stove, electric iron etc
4. Sound energy in to electrical energy-----microphone
5. Chemical energy into electrical energy----Battery. Lead accumulator
Q 6) Describe the mode of energy transformation in a mechanical and quartz clock.
Ans: In a mechanical clock mechanical potential energy into kinetic energy In a quartz clock
electrical energy into magnetic energy and then kinetic energy
7) what kind of energy transformation takes place at the thermal power station.
Ans:
In thermal power station heat energy converted into electrical energy..
WORLD OF SOUNDS
Texual Questions and Answers
I.
Four aleternative are given to each of the following
incomplete statement/question. Choose the right
answer
1.
Imagine that you are listening to a populars song from a radio. Using
volume control knob, you slightly increase the volume. The factor
related to sound wave in this process is, increase in
a) Frequency
c) amplitude
b) Velocity
d) both frequency and wave length
(c)
2.
The velocity of sound is highest in
a) Air
c) glass
b) Water
d) vaccum
(c)
3. In an unoccupied hall of a choultry you will experience the echo effect of
sound. If the same hall is furnished with almirahs, tables, chairs and
other commodities, you may not experience the echo clearly. It is
because.
a) Sound waves get absorbed by the objects in the hall
b) The area of reflecting surface decreases
c) Reflected sound is reflected again
d) Sound does not get reflected
(a)
4. The factor that is transmitted in wave motion is
a) Particles of the medium
b) Vibrations of particles
c) Energy of the cause of the wave
d) Electrons of the medium
II.
(c)
Fill in the blanks with suitable words:
1. The product of frequency and wavelength of a sound wave is equal to its
……….(velocity)
2. The S.I. unit of wavelength is ………..(metre)
3. The velocity of sound in air at 25 0C is approximately ………(0.346kmper
second)
III.
Answer the following:
1. Why is sound a longitudinal wave?
Ans: Sound wave is an energy which forms compression and rarefaction in
air particles. These compressions, rarefactions form a longitudinal wave.
2. Explain an activity to show that sound can do work.
Ans : Blow a bugal, it produces sound and the energy produces
compressions and rarefactions. Due to this a force is created and it pushes
the air particles up to certain distance. Hence we can show that sound can
do work.
3. Describe an activity to show that sound is produced by vibration of
materials.
Ans : Take at tuning fork (a “U” shaped metallic thing) and strike is to a
hard object. Bring the fork near your ear, you can hear the sound. Then just
dip one end of the fork on the surface of water, it will be found that
vibration of the fork. This shows that vibration produces sounds.
4. Make a list of five musical instruments. State how each of them produces
sound.
Ans :
Musical instrument
The way it produce sound
Violin
Vibration of string
Drum
Vibration if diaphragm
Flute
Vibration of air
Tabla
Vibration of diaphragm
Saxophone
Vibration of air
5. List two applications of reflection of sound.
Ans : 1. Gol Gumbaz in Bijapur of Karnataka, produces echo of
sound seven times.
2. A Broad spacious empty room produces reflection of
sound. This is helpful to hear echo of jaz music.
6. Describe an activity to show that sound requires a material
medium for its propagation.
Ans: For diagram refer page No. 158 fig 14.7
Suspend a mobile phone inside any air tight glass bell jar as
shown in figure. Connect the bell jar to a vacuum pump. When you call
the phone number you can hear the ring tone. Now remove the air from
the bell jar by using a vacuum pump. Observe the phone and changes in
the sound. What happens to the strength of the sound ?
The sound goes on decreasing and finally you cannot hear the
sound. From this activity we come to a conclusion that material medium
or required for the propagation of sound.
7. Represent a wave graphically. Show in the diagram, the
wavelength and amplitude.
Ans: Refer the page No 159 fig 14.8
Think:
1. why is sound both a boon and bane ?
Ans: When we hear appreciable musical sound, it gives us happiness. It
is proved that a beautiful melodious sound inspires our mind and
improves mental health. Hence sound is a boon.
If the sound is loud and irritable, it creates headache and loss of
concentration, hence sound is a bane.
2. What measures would you take to minimise the sound
disturbance cause to others.
Ans: First and foremost, request the persons responsible for
causing sound disturbance. Ask them to reduce the volume of the sound.
Ask them to use low power sound output, so that only the audience can
hear the sound in low voice. Supreme court has banned public
performance of sound system after 10.30 p.m. This must be strictly
followed.
HEAT
I Tick the correct answer
1) when an object is heated the molecules that make up the object
a) begin to move faster.
b) lose energy
c) became heavier
d) become lighter
2) The temperature of a body in an indicator of
a)the total energy of the molecules of an object
b)The average energy of the molecules of the object.
d)The average kinetic energy of molecules of an object.
3) A and B are two objects. The temperature of A is greater than that of B.This means that
a)the molecules of A move faster on an average than the molecules of B.
b)The total energy of A is greater than the total energy of the molecules of B.
c)the average potential energy of A is greater than the average potential energy of B.
d)The heat contents of a will always be greater than that of B.
II Fill in the blanks with suitable words.
1) The degree of hot or cold of a body is called temperature.
2) Temperature is expressed in degree centigrade.
3) When a body changes from liquid to gas at constant temperature it is called boiling
point.
4) The temperature of boiling water in the Celsius scale of temperature is 100 .C
5) The S.I unit of heat is Joule
III True or false
1. Liquids expand on heating True
2. The unit of heat and temperature are the same False.
3. Bimetal strip is used in fan False
IV Match th following
1) Formation of ice bergs  anomalous expansion of water.
2) Rise of mercury level in thermometer thermal expansion
3) Automatic electric iron bimetal-strip.
4) Cracking of hot glass platinum touched by cold objects Sudden Contraction
V Answer the following
1) Distinguish between heat and temperature
Ans:
Heat
1) Heat is a form of energy
2) Heat energy depends upon the speed of the particles.
3) S.I unit of heat is Joule.
Temperature:
1) Temperature is a measure of degree of hot or cold. It is number that is related to
energy.
but , it is not energy .
2) Temperature does not depend on the size or mass of an object. For example
temperature of a small cup of water is the same as the temperature of a tub of water. But the tub
of water has more heat becauseit has more water and thus more total thermal energy.
3) S.I unit of temperature is Kelvin.
2) Mention three different effects produced by heat.
Ans:
The three different effects produced by heat are:
1) If we provide heat to a substance its temperature increases.
2) Heat energy result in the expansion or contraction of solid , liquid or gases.
3) Change of state in the substance is produced by heat eg. Solid converts to liquid and
gases
3) Give one example that heat can be generated from the energy motion.
Ans: When we rub our hands one another for a long time, heat is generated. Rubbing creates
motion of hands and friction between the hands creates heat.
4) Describe an expression to prove solids expand on heating
Ans:
Expansion of Solid
Take two aluminum rods measuring about 7 cm each. Fit and connect as shown in the
diagram. keep paper thin gap between both the rods. Now heat the rod. the bulb start to glows,
because the heated rod expands . and touches the other rod to complete the electric circuit. This
experiment shows that solids expands on heating .
5. Name two divices which use bimetallic strip.
Ans: The two devices which use bimetallic strip are eg. refrigerator , Automatic electric iron box
5) A thick glass tumbler often crack when boiling water is poured in it why?
Ans: If we put boiling water in thick glass tumbler it cracks immediately. This is due to the fact
that glass is a poor conductor of heat. When boiling water is poured in the glass the inner
surface of glass expand quickly , but the outer surface of the glass does not expand quickly this
uneven expansion cracks the glass.
6) state similarities and difference between the laboratory and clinical thermometer.
Ans Similarities between laboratory thermometer and clinical thermometer.
1. Both are made of glass. 2. The property of expansion of liquids (mostly mercury )
On heating is used in both thermometers. 3. Both the thermometer are marked with
measurements in Celsius and Fahrenheit.
7) Differences between laboratory thermometer and clinical thermometer.
1) Laboratory thermometer is much longer than clinical thermometer.
2)Laboratory thermometer is used measure temperature or temperature changes in high
degree of precision But clinical thermometer is used to measure human and animal body
.temperature with low degree of precision. 3) Laboratory thermometer contain a long tube
without any construction . But clinical thermometer has a construction near the bulb containing
mercury.
8) Convert 100.F in to Celsius and Kelvin scale of Temperature.
Ans:
F = 9/5 C + 32
100 = 9 C + 32 o r 9 C = 68
5
5
0
C= 68 x 5 =37.7 C
9
Under Kelvin scale
273 + 37.7 0 = 310. 7 K
5-Our Colourful world
I Tick the correct answer
1) Rear view mirror of motor vehicles contain
a)place mirror
b)convex mirror
c)concave mirror.
d)convex lens
2)If a ray of light is travelling from denser medium to rare medium and if the angle of
incidence is grated than critical angle than the following takes place
a)reflection
b)refraction
c)dispersion
d)multiple refraction
3) A concave mirror forms magnified inverted image when the object is placed at
a) ’F’
b) ’C’
c) between ‘F’ and ‘C’
d)beyond ‘C’
4) on a new stainless steel spoons of you see the image of your face upside down then
that part of the spoon acts like
a)convex lens
b)concave mirror
c)convex mirror
d)concave lens
2) You can see the image of your face on the surface of skill water but if the water is
disturbed your image will not be clear because of
a)total internal reflection
b)refraction
c)irregular reflection
d)dispersion
III Fill in the blanks
1) The letter ‘P’ looks like q in a plane mirror.
2) Water repairs use the lens of the type convex.
3) Bending of light when it passes from one transparent medium to another is called
refraction
4) Formation of rainbow is due to dispersion of light
III Answer the following
1) Give one reason to prove that light is a form of energy.
Ans:When light falls on photo electric cells it converts to electrical energy. Therefore light is a
form of energy.
2) What are the differences between regular and irregular reflection?
Ans: During regular reflecting a proper image is formed. Pattern of incident rays and refracted
rays are same But during irregular reflection image formed is scattered and the reflected rays
completely out of pattern
3)
State the laws of reflection
Ans: The laws of reflection are:
1) Angle of incidence is equal to the angle of reflection
2) The incident ray the normal drawn to the mirror at the point of incidence and the
reflected ray all lie on the same plane.
1) Mention the uses of concave mirror?
Ans:
1.
Concave mirror are used in head lights of vehicle.
2. Concave mirror is used as mouth mirror by dentist.
3. Concave mirror is used in solar furnace
2) why is convex mirror used as rear view mirror in motor vehicles?
Ans: Convex mirror reflects the vehicles coming from rear side and it is possible to recognize
the vehicles clearly in small size and allow them to pass through.
3) Mention any two effect of refraction of light in daily life?
Ans:
The two effects of refraction of light in daily life are:
1)The bottom of a water tank appears to be raised.
2)Twinkling of stars at night is due to refraction of light from stars.
4) what are conditions for total internal reflection to take place?
Ans:
The condition for total internal reflection are
1)Light ray should pass from denser medium to rarer medium.
2)The angle of incidence must be higher than critical angle.
5) Mention any four devices that contain convex lens.
Ans: The four devices that contain convex lens are microscope, Astronomical telescope
camera , and lens used by watch repair
6) what is dispersion of light?
Ans: The splitting up of white light into its constituent colours is called dispersion of light.
Q 10 Write the diagrams to show the refraction of parallel rays of light in
1)convex lens.
2)concave lens.
1)convex lens.
2)Concave lens
11) Draw ray diagrams of convergence and divergence of light rays in a convex lens
and concave lens
Ans
Convergence of light rays in convex lens.
Divergence of light rays in concave lens.
IV Match the following
1)Dispersionrainbow
2)diminished image
convex mirror
3)enlarged image concave mirror
4)Total internal reflectionMirage
6-Communication Gadgets
I Tick the correct answer
1) Modulated waves of radio transmitter contains.
a)Sound waves
b)carrier waves
c)AF waves and carrier waves
d)AF waves
2) Increasing the strength of AF waves is called
a)modulation
b)transuding
c)demodulation
d)amplification
3) Telephone with cables was invented by
a)Alexander fraham Bell
b)Alexander bain
c)Martin Cooper
d)John Logie baird
4) A person is singing in a radio station. It can be listened to in a receiver almost at a speed of
a)Sound
b)light
c)1/16 th of second
Ans ( d )
th
d)1/10 of a second
II Fill in the blanks
1) The device that can be used to send a copy of a document to other place quickly is fax.
2) Original sound is reproduced in radio receiver by speaker
3) First person to demonstrate transmission of radio signals is J.C.Bose
4) Two ways radio communication device is called mobilephone.
5) Radio communication of long distance is possible without satellites due to the
presence of atmospheric layer Ionosphere.
6) Microwave are used in mobile phones.
III Answer the following
1) What are electromagnetic waves?
Ans: Mutually perpendicular Electric and magnetic fields which are also perpendicular to the
line of propagation are known as electromagnetic waves..
2) What is modulation?
Ans:
The process of superimposing or mixing AF signals on RF waves is called modulation.
3. Which part of radio transmitter converts sound waves into audio frequency waves?
Ans Microphone converts sound waves into audio frequency waves.
4. which part of the T.V transmitter converts light into electrical signals?
Ans:
Photo cells in the T.V camera convert light into electrical signals.
5. Draw a neat block diagram of radio transmitter?
Ans:
Block diagram of radio transmitter
Refer page no. 261 fig 21.6
. Microph
AF
sound
one
signals
sound
amplifie
s AF
Amplifie
r AF
signals
Modula
tion
AF+RF
Amplific
ation
Antenna
RF waves
6. The principal of radio and mobile phone is same. how are the two different from one
another.?
Ans:
Radio
1. Radio has transmitter
and receiver separate
Mobile phone
Mobile consists of both transistor
and receiver
3. Only sound can be heard
no display screen
4. There is tuning
5. Uses radio waves
6. It is not possible to send
Our messages through
Receiver
7. Not possible to send
SMS and MMS
Display screen is there
key board is there
uses micro waves
It is not possible to send
and receive any messages
possible to send SM S and MMS
BEYOND THE EARTH
Textual Question and Answer
I. Four alternatives are given to each of the following incomplete
statement/question. Choose the right answer
1. The constellation that helps to locate north star is
a) Cassiopeia
b) Orion
c) Taurus
2.
a)
b)
c)
d)
d) Leo
The second biggest planet of the solar system has
lowest density
density equal to water
highest density
density equal to earth
(a)
(a)
3. The poles of this planet faces the sun for longer periods of time than any other planet
a) Mars
b) Uranus
c) Jupiter
4.
a)
b)
c)
d)
d) Saturn
(b)
Polar ice caps of the planet mars are due to
solidified water
solidified carbon dioxide
Volcanoes erupted near the poles
cover of dust particles that reflect light
(b)
5. Heat waves are trapped to maximum in the planet.
a) Mercury
b) Venus
c) Earth
d) Neptune
(b)
II. Fill in the blanks with suitable words
1. Radio signals are emitted by the planet _ _ _ _ _ _ _ _ (Jupiter)
2. The colour of the planet mars in _ _ _ _ _ _ _ _ _ _ _ _ (Red)
3. Winter season constellation is _ _ _ _ _ _ _ _ _ _ _
(Cassiopeia)
4. Asteroids are mainly found between the orbits of _ _ _ _ _ _ _ _
(Mars and Jupiter)
5.Ultraviolet rays from the sun can be filtered by the earth’s atmospheric layer called _ _ _ _ _ _
_ _ (ionosphere)
III. Match the following
A
1.
2.
3.
4.
B
highly tilted planet
Satellite of Jupiter
Constellation
Third planet from the sun
Ans: 1.e
2.d
3.f
a) Earth
b) Titan
c) Halley
d) Io
e)Uranus
f)Ursamajor
e) Sirius
4.a
IV. Answer the following questions
1. Which planet is called morning or evening star ?
Ans: Venus is called morning or evening star.
2. Which planet was removed from the list of 9 planets in 2006 ?
Ans: Planet pluto was removed from the list of 9 planets in 2006.
3.
a)
b)
c)
Express the following in km.
10 light minutes
10 light days
10 light years
Ans: a) 10 light minutes = 18x107 km
b) 10 light days
= 2592x108 km
c) 10 light minutes = 94608x109 km
4. Name the following:
a) The most fascinating planet with set of ring system as viewed from
a telescope.
Ans: Saturn
b) Nearest planet to the earth
Ans: Venus
c) Nearest planet to the sun
Ans: Mercury
d) Biggest planet of the solar system.
Ans: Jupiter
5. Why do comets develop tails as they approach the sun.
Ans: Comets are made up of silicates and frozen gases. When they approach the sun they
develop tail because of heat and light pressure of the sun.
6. How are satellites different from planets
Ans: Planets
1. Large in size and mass.
2. Revolve round the sun
3. Altogether there are eight planets.
Satellites
1. Small in size and mass.
2. Revolve round the planets
3. There are many number of satellites for different planets, except for mercury and venus
which have no planets.
7. Which satellite has active volcanoes ?
Ans: Satellite Io of Jupiter has active volcanoes.
8. Give reason for the following:
a) A person in England can recognize the pole star easily than a person in Bangalore.
Ans: England is very near to the north pole, hence a person in England can recognize the pole
star.
b) Mercury is difficult to observe.
Ans: Planet mercury is very near to the sun. Due to bright sunlight it is difficult to observe.
c) A day no Venus is longer than its year.
Ans: Because Venus rotates about its axis slower than its revolution around the sun.
d) Green house effect is prominent on venus
Ans: There is abundant of carbon dioxide on Venus hence Green house effect is prominent.
V. State true or false
1. Saturn has highest density
Ans: False
2. Venus can be seen over head in the night sky
Ans: False
3.Aries (Masha) is Zodiacal constellation
Ans: True
4. Moon has no atmosphere
Ans: True
5. Titan is the satellite of Jupiter
Ans: False
6. Mars contains oxgygen in its atmosphere
Ans: True
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