Download PHYSICS 1-Describing Motion - Uday Pre

PHYSICS
1-Describing Motion
I Fill in the Blanks
1. When an object is in uniform motion then its path looks like a Straight line.
2. S.I unit of speed is meter per second [ms-1]
3. S.I unit of displacement is meter.
4. A body starting from reset has initial velocity O
5. Displacement per unit time is velocity.
6. Change in the velocity of an object in unit time is acceleration.
7. S.I unit of acceleration is metro per second per second [ms-1]
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: The object completes one full cycle it comes back to its original position so displacement is
O
Distance travelled by an object=Circumference of the path= 2𝜋
=2X22/7X3.5
=22/7 X7
=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
a=V-U =40-30 =10=5 ms-2
t
2
2
1
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
1+2 3
A=V-U= 7/3-0 = 7 = 7 =0.7 ms-2
T
3
3X3 9
II Answer the following
1) In a body is moving with uniform velocity in a given direction its acceleration will be zero
why?
Ans: A body is moving with uniform velocity in given direction its acceration will be O because
there is no change in direction.
2) Distingiush between speed the velocity.
Speed
1 Scalar quantity
travelled per unit time
Velocity
1.vector quantity
displacement per unit
time
Ans:
3) Distingiush between distance travelled and displacement.
Ans:
Distance
displacement
1.it is the length of the
actual path covered
Displacement
1.Shortest distance
between initial and
final velocity
4) what are uniform and nonuniform motions?
Ans: when a object covers equal distance in equal interval of time the motion is said to be uniform
motion. when the body covers unequal distance in equal intervals of time motion is said to be non
uniform motion.
5) while mentioning acceleration the time is mentioned two times why?
Ans: since acceleration in change in velocity per unit time. time is mentioned once in the definition
of velocity and once while defining of acceleration.
2
2-Force and Newton’s Law of motion
I Tick the correct answer.
1) Action and reaction
a)act on the same body/
b)are equal
c)are opposite
d)act on different bodies.
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 losses its shape.
3) The S.I unit of force
a)Newton’s
b)Newton
c)Newton’s
d)Newton
II Fill in the blanks:
1) Inertia of an object is proportional to its mass.
2)To cause acceleration in an object the necessary factor is unbalanced force.
3)The S.I unit of momentum is kgms-1.
4)Newton’s first law of motion is also called law of inertia.
5)The suitcase kept in a moving bus ,move forward when the braker are applied suddenly.
This is due to Inertia.
III Answer the following
1) In a tag war game ;if the two teams exert equal forces, none of the team wins. why?
Ans:if equal forces are exerted by two teams there is no change in position. since force are balanced
force.
2) which of the following has greater momentum?
Ans a):An object of mass 2kg moving with uniform velocity of 2 ms-1.
Momentum=mv=2X2=4ms-1
b)an object of 1 kg mass moving with uniform velocity of 3 ms-1.
Therefore the object of mass 2 kg velocity 2 ms-1 has greater momentum.
3
3) which of the following has greater inertia?
a)50 paise coin.
b)1 Rupee coin
c)5 Rupee coin.
Ans: 5 rupees coin ha greater interia as it has more mass.
4) state any two illustration for Newtons third law of motion?
Ans: a)when a bullet from a gun, the gun recoils with an equal force in opposite direction.
b)Swimmer while swimming pushes water backwards and turn he moves forward.
5) Distingiush between balanced and unbalanced forces.
Force
If balanced force
acting on an object
changes its speed and
direction
Unbalanced force
If balance acting on
an object there is no
change in its position.
Ans:
6) state newton’s second law of motion in terms of momentum.
Ans: Newtons second law motion can also be stated as rate of change of momentum is directly
proportional to the impressed force and take place in the direction of the application of the force.
IV give reasons.
1) It is dangerous to get down from a moving bus even if the bus is moving slowly.
Ans: Because due to inertia one may fall and get hurt.
2) An athlete in long jump runs a distance before taking the leap?
Ans: So that he attains the required momentum before taking the leap.
3) usually a field in a cricket match takes a catch by moving his hands in the direction of
motion of cricket ball.
Ans: otherwise he will hurt his hand due to inertia.
V Solve the problems:
1) Calculate the force required to change the velocity of an object of mass 8kg 4ms-1 to 6ms-1 in
2 second.
Ans: Mass8kg
u4ms-1
v6ms-1
t2
F=m X a
F=m X a
a=?
F=8X1
a=v-u a=6-4=1 ms-2
F=8N
t
2
Therefore force is 8N
4
2) A force of 25 newton is applied on an object of mass 10 kg. moving with a velocity of 5m/sIf the object gains a velocity of 10ms-1,calculate the time interval.
,

F=25N
a=?
M=10kg t=?
F=ma 2.5
a= F = 25 =2.5ms-1
m
10
v=u+at
V=o ms-1
U=O
A=2.5ms-2
t=v-u = 5-0 = 5 =2 sec
a
2.5 2.5
Therefore time is 2 sec.
3) write Newton’s law of motion
Ans: The Newton’s law of motion are:
1) I law of motion:
Everybody continues in its state of rest or of uniform motion in a straight line, unless
it is compelled to change that state by force impressed on it.
2) II law of motion:The accerleration given to a body by a force applied to it is directly
propotional to the force and is in the same direction of the force and inversely proportional
to the mass of the body.
3) III law of motion: To every action there is always an opposed and equal reaction.{action and
reaction are equal and opposite.}
5
3-Energy and Its Forms
I Fill in the blanks
1.
2.
3.
4.
5.
Unit of power is watt.
Unit of energy is Joule.
If a candle is burnt, the chemical energy is transformed into light energy.
The water stored in an overhead tank possesses potentional energy.
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= sqr root2K/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
6
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
The energy that the body possesses due to its The energy which a body posses either due
motion is called kinetic energy
to its position or due to its deformation is
called potential energy.
3) A bus and a car are moving at the same speed. which of the two has a greater kinetic
energy?
Ans: a bus has grater kinetic energy than car because kinetic energy is directly proportional to the
mass of the object.
4) 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)
Ans:
m=200gram or 0.2kg
H=5m
G=9.8ms-2
P.E=m X g X h
P.E=0.2 X 9.8X 5
P.E=9.8 J
As the ball reaches the ground potential energy is converted into kinetic energy so K.E=9.85
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.Bulb 2.Motor 3.Heater 4.Microphone 5. Dry cell
7
6) Describe the mode of energy transformation in a mechanical and quartz clock.
Ans: In a mechanical clock spring inside gets wound and potential energy in the spring is
converted into kinetic energy due to which the hand of clock move. In a qurat clock a dry cell is
used chemical energy is converted into electrical energy which turn into mechanical energy which
make the hands of clock move.
7) what kind of energy transformation takes place at the thermal power station.
Ans: chemical energy of coal is converted it heat energy in the steam which is converted into
mechanical energy in the turbine which turn converted into electrical energy..
4 - World of sound
I Fill in the blanks
1) The product of frequency and wavelength of a sound wave is equal to its velocity.
2) The S.I unit of wavelength is meter.
3) The velocity of sound in air at 25. C is approximately 346m/s.
II Tick the correct answer.
1) Imagine that you are listening to a popular song from a radio.using volume control knob,yoi
slightly increase the volume..The factor realated to sound wave in this process is increase in
a)frequency
b)velocity
c)amplitude
d)both frequency and wavelength.
2) The velocity of sound is hightest in glass
a)air
b)water
c)glass
d)vaccum
3) In an unoccupied hall of a choultry you will experience the echo effect of sound.tf the same
hall furnished with almires, tables, chairs and other commodities, you may not experience the echo
clearly it.
a) sound waves get absorbed by the objects in the hall.
b) the are of reflection surface
c) reflected sound is reflected again
d) sound does not get reflected.
8
4) The factor that is transmitted in wave motion is
a) Particles of the medium
b) Vibration of particles.
c) Energy of the cause of the wave.
d)electrons of he medium.
III Answer the following
1) Why is sound longitudinal wave?
Ans: Sound is a longitudinal wave as the particles of the medium vibrate in the direction of
propagation.
2) Explain an activity to show that sound can to work.
Ans: A Take a thin strip of paper and hold it against sound from a loud speaker. The strip of paper
moves in the sound this indicate that sound can do work.
3) describe an activity to show that sound is produced by vibration of materials.
Ans: Take a rubber string. stretch it tightly between two supports plucks the string. The string
begins ti vibrate. we can hear some sound.
4) Make a list of five musical instruments. state how each of them produce sound.
Ans:
Musical Instrumental
The way it produce sound
1 veena
2.vilon
3.flute
Vibration of string
String vibration of string
Vibration of air coloum.
4.sitar
5.mridangam
Vibration of string
Vibration of membrane
5) List two applications of reflection of sound.
Ans: Reflection of sound finds some wonderful applications in fields such as industry medicine and
entertainment.
6) Describe an activity to show that sound requires a material medium for its propagation.
Ans: suspend a mobile phone inside an airtight glass bell jar. connect the bell jar to a vaccum pump
when you call the phone number you can hear the ring tone. Now remove the air from the bell jar by
using the pump. observe the phone and the changes in the sound By this we can show that sound
requires a material, medium for its propagation
9
7) represent a wave graphically. share in the diagram the wavelength and amplitude.
wavelength
Amplitude
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.
10
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. The number of particles and the size
or mass and the type of particle in an object.
3) S.I unit of heat is Joule.
Temperature:
1) Temperature is a measure of degree of hot or cold. It is numn that is related to energy. but
it is not energy itself.
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 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) Increase in temperature.
2) Change in physical state[expansion of solid]
3) Thermal expansion.
3) Give one example that heat can be generated from the energy motion.
Ans:
When ice rub both our palms our palms become hot by this heat energy is produced.
11
4) Describe an expression to prove solids expand on heating
Ans:
Expansion of Solid
Take two aluminum rods of same length, connect as shown in the diagram. keep paper then
gap between both the rods. Now heat the rod. the bulb start to glowing (The rod come into
contact)then remove the flame the light goes off. this shows solids expand on heating.
5) Name two divider which use bimetallic strip.
Ans: The two devices which use bimetallic strip are microwave oven, iron box etc.
6) 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 put in the glass tumbler the inner surface
of glass. Expand the outer surface of the glass does not expand quickly this uneven expansion cracks
the glass.
7) state similarities and difference between the laboratory and clinical thermometer.
Ans:
Similarities
1)Both the thermometer are made up of glass.
2)both the thermometer use mercury.
Differences
1)Laboratory thermometer is used measure temperature changes in high degree of precision
its range starts from OoC.
2)Clinical thermometer is sued in clinical use of human and animal .Its range starts from
35oC
12
8) Convert 100.F in to Celsius and Kelvin scale of Temperature.
Ans:
T o convert 100.F into 0C
We multiply 5/9(100-32) =340/9=37.70C
To Convert 37.7into K we add 273K= 37.7oC+273=310.7
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
5) 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
13
III Fill in the blanks
1) The letter ‘P’ looks like 9 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
III Answer the following
1) Give one reason to prove that light is a form of energy.
Ans: Light can do work. It can activate our eyes. Plants carry out photosynthesis with the help of
light energy and prepare food
2) What are the differences between regular and irregular reflection?
Ans: The difference between regular and irregular reflection are:
1)
regular reflection:
In a perfectly flat surface or polished surface
There is regular refraction which enable to form an image.
2)
Irregular reflections:
Objects having rough surface reflect.
Light in all directions. Light get scattered and images are not formed.
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
4) Mention the uses of concave mirror?
Ans:
Concave mirror are used by dentists and in solar furnace and in head lights of motor vehicle.
5) why is convex mirror used as rear view mirror in motor vehicles?
Ans: Convex mirror are used as rear view mirror in motor vehicles because convex mirror always
produce diminished virtual image of an object.
14
6) 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)pencil partially immersed in an oblique manner in water appears to be bent.
7) 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.
8) Mention any four devices that contain convex lens.
Ans:
The four devices that contain convex lens are camera, microscope, telescope and binnacles.
9) 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.
15
2)Concave lens
11)draw ray diagrams of convergence and divergence of light rays in a convex lens
and concave lens
Ans
16
IV Match the following
1)Dispersionrainbow
2)diminished image concave lens
3)enlarged image convex lens
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
d)1/10th 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
17
3) First person to demonstrate transmission of radio signals is J.C.Bose
4) Two ways radio communication device is called mobile.
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:
Electric and magnetic fields which are also perpendicular to the line of propagation are
known as electro magnetic waves. They travelled with a velocity of 3X10 8 ms-1 in vaccum
2) What is modulation?
Ans:
The process of superimposing or mixing AF signals on RF waves is called modulation.
3) which part of the T.V transmitter converts light into electrical signals?
Ans:
In T.V transmitter photo cells convert light into electrical signals.
4) which part of the Radio transmitter converts sound waves into AF waves?
Ans:
In radio transmitter ‘microphone’ converts sound waves into AF waves.
5) Draw a neat block diagram of radio transmitter?
Ans:
Block diagram of radio transmitter
Refer page no. 262 fig 21.8
. Microph
AF
sound
one
signals
sound
Amplifie
r AF
signals
Modula
tion
AF+RF
amplifie
s AF
Amplific
ation
Antenna
RF waves
6) The principal of radio and mobile phone is same. how are the two different from one
another.?
Ans: Principal of radio and mobile phone is same. Mobile phone is two way radio system. as it
consist of both transmitter and receiver.
18
7-Beyond the Earth
I Tick the correct answer:
1) The constellation that helps to locate north star is
a) Cassiopeia
b) Orion
c) Taurus
d) Leo
2) The second biggest planet of the solar system has
a) lowest density
b) density equal to water
c) highest density
d) density equal to earth
3) The poler of this planet faces the sun for longer period of time than any other planet
a) mars
b) Uranus
c) Jupiter
d) Saturn
4) Polar ice cups of the planet mars are due to
a) solidified water.
b) solidified carbon dioxide
c)volcanoes erupted near the pole
d)cover of dust particles that reflect light.
5)Heat waves are trapped to maximum extent in the planet
a) Mercury
b)Venus
19
c) earth
d)Neptune
II match the following
1.Highly tilted planet
2.Satellite of Jupiter
3.Constellcation
4Third planet from the sun
Uranus
Jo
Ursa Major
earth
III Fill in the blanks
1) Radio signals are emitted by the planet Jupiter
2) The color of the planet Mars is Red
3) Winter season constellation is Orion
4) Asteroids are mainly found between the orbits of Mars and Jupiter
5) Ultraviolet rays from the sun can be filtered by the earths atmospheric layer called
stratosphere (Ozone layer)
IV Answer the following
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: Pluto was removed from the list of 9 planets in 2006
3) Express the following in Km
a)10 light minutes
10X60X300000 km
b)10 light days
10X24X60X60X300000 Km
c)10 light years
10X365X24X60X60X300000 km
4) Name the following
a) most fascinating planet with set of ring system as viewed from a telescope
Saturn
b)Nearest planet to earth
20
Venus
c)Nearest planet to sun
Mercury
d) Biggest planet of the solar system?
Jupiter
5) which satellite has active volcanoes
Ans:
Io the satellite of Jupiter has active volcano
6) how are satellite different from planets.
Ans: planets revolve around sun and satellites revolve around their respective planets.planets have
atmosphere but satellites do not have atmosphere.
7) why do comets develop tails as they approach the sun?
Ans: comets are made up of frozen gases as the comets approach the sun they start melting due to
the heat .So their tails are formed.
8) give reason for the following:
a)mercury is difficult to observe
Mercury is the nearest planet to the sun. Sun rises or sets within about two hours of
mercury’s rising or setting
b)A day on Venus is longer than its year
Venus period of rotation is 243 days and takes 224 days to go around the sun once. so a
day on venue is longer than its year.
c)Green house effect is prominent on Venus
Carbon dioxide block long wavelength infrared radiations and heat is trapped inside, so
green house effect is prominent Venus.
d) a person in England can recognize the poll star easily than a person in Bangalore.
The pole star can be easily seen from the north side and even England lies in the north and
Bangalore lies in south so a person in England can recognize the pole star easily than a person in
Bangalore.
21
V state weather true or false
1)Saturn has highest density false
2)Venus can be seen overhead in the night sky.false
3)Aries is a zodiacal Constellationtrue
4)Mars contains oxygen in its atmospheretrue
5)moon has no atmospheretrue
6)Title is the satellite of JupiterFalse
22