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The PHENOMENON of change of liquid into VAPOURS at any temperature below the boiling point of liquid is called evaporation. evaporation is also called as endothermic process. Factors affecting the rate of evaporation are: i) surface area - evaporation bein a surface area phenomenon, the rate of evaporation increases with increase in surface area. ii) temperature - the rate of evaporation increases with increase in temperature. iii) humidity - humidity is DEFINED as the amount of water vapour present in the air. the rate of evaporation decreases. iv) wind speed - the rate of evaporation increases with increase in wind soeed. and increase in speed if wind causes water vapours particle to move AWAY with the eind and this decreases the amount of water vapours in the surroundings. hope it helped you!!!

BY WORK ENERGY THEOREM
WORK DONE IN STOPING  = CHANGE IN KINETIC ENERGY =
                                                                    
=

=208333.333 Joule

we get dew on the SURFACE of a cold soft drink bottle KEPT in  air because when that the temperature of surrounding air is higher than the temperature of the cold soft drink. Air contains water in the FORM of vapour. When the molecules of water in air, during their motion, strike the surface of the bottle which is cool. They lose their kinectic energy which LOWERS their temperature and they get converted into DROPLETS.   

The moon does not appear similar on different days rather its shape changes every day. The different shapes of the moon are called the phases of moon.New Moon: On the new moon day, no moon is visible in the sky.
Waxing Crescent: Within a few days of the new moon day; the moon appears like a crescent. This is called the waxing crescent.1st Quarter: Within about a week from the new moon day; the moon appears as a SEMICIRCLE. This is called the 1st quarter moon.
Waxing Gibbous: Within about 10 days from the new moon day; the moon appears as a circle with some portion cut off. This is called the waxing gibbous moon.
FULL Moon: Within about 15 days from the new moon day; the moon appears as a complete circle. This is called the full moon.
Waning Phase: The waxing phase of the moon is followed by the waning phase. During this phase; the full moon reduces in size and goes through the waning gibbous, 2nd quarter and waning crescent phases. Within about 29 days from the new moon day; the next lunar month begins with the next new moon.
Reason for Phases of Moon: The periods of rotation and revolution are same in case of the moon. This means that the moon takes the same time in completing one rotation and one revolution. DUE to this, only one surface of the moon is visible from the earth.

1.it is used in SPECTACLES by people who have difficulty to see DISTANT objects
2.dentists USE it to GET a enlarged image of SMALL parts of teeth
3.shaving mirrors consists of concave mirror

Let the mass of the light body = m kg ,  its velocity = v m/s.
Let the mass of the HEAVY body = M kg,   M > m , its velocity V m/s.

    KE = (mv)²/ (2m)  =  (MV)²/(2M )   
             (mv)²/(MV)² = m/M   < 1        =>   mv < MV
 The HEAVIER body has higher momentum.
===================================
2)  lighter body:  m kg and  velocity V m/s
     heavier body :  2 m  and  velocity V/2 m/s
       Their momentum is same.
   But    KE :  1/2 m V²   :  1/2 (2m) (V/2)²
             KE :    1 :  1/2 
      The lighter body has a higher KE
============================
3) 
    DRW trucks are used for very heavy load carrying trucks.  For lighter loads, they are not really advantageous.  The additional wheels add some weight on the rear suspension.  Then the springs on the rear suspension have to be stiffer (higher spring constant), to handle them.

   The area between the tyres is LESSER as compared to the SRW trucks.  So if there are bumps or if the road is rougher, then the truck dances more.  There is more stress on the axle parts and the body.Cost of the wheels and the related maintenance is added.For very heavy trucks, the load is evenly distributed on tyres.  So the pressure is reduced.  The trucks can carry higher loads.  For very long and higher trucks, is important.  SRW may be able to control the sideways pull (sway).

In actual the RAINBOW is in the shape of complete CIRCLE... but we are not able to see the complete ONE because of the shape of the EARTH.........

So we see at the top most point the VELOCITY the boy is zero and the EARTHS pull is acting downwards

Given     

⇒ 


so using

v² = u² - 2gs            where g = acceleration due to gravity
                                       s = total HEIGHT

so 

0 = u² - 2gs  

⇒ s = 

⇒ 2 = 

PUTTING    

⇒  2 = 

⇒12 = 

so the boy can jump a height of 12 m on MOON's surface

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Convex lens f = +40 cm  as the principal FOCAL point is in the direction of the rays.
concave lens = -50 cm as the principal focal point is on the side of the object.

combination of thin lenses:  1/f = 1/f1 + 1/f2 = 1/40 - 1/50 = 1/200 
    f = 200 cm  POSITIVE so convex lens

P1 = 1 /(40/100) meter = 2.5 Dioptre
P2 = 1/(-50/100)m = -2 D 

power of combination = P = P1 + P2 = 2.5 - 2.0 = 0.5 D
                or,  1/(200/100)m   = 1/2 = 0.5 D

Water has higher specific heat. And for that reason, it can act as effective heat bank for our atmosphere. A small change in the temperature of water is accompanied with RELEASE or absorption of high amount of energy. When the surrounding air HOT(in summer), water can absorb heat from atmosphere and either become vapour or just store it by increasing its temperature and as a result, cools the surrounding. When the surrounding air is COOLER(in WINTER). water can release the STORED energy as heat and raise the surrounding atmospheric temperature. So water helps in maintaining a balanced temperature of the atmosphere and it can do so due to its high specific heat energy.

M = 70 kg
v = 9 kmph = 9 * 5/18 = 2.5 m/s
u = 18 kmph = 18 * 5/18 = 5 m/s

Work done  = CHANGE in kinetic energy
              = initial KE - final KE
              = 1/2 m u² - 1/2 m v²
              = 1/2 * 70 * 5² - 1/2 * 70 * 2.5²
            = 875 J - 218.75 J  = 656.25  J

 The speed has come down to half its VALUE.  But the Kinetic energy becomes 218.75/875 = 1/4 TH of inital KE.

M = 100 gm
h = 40 m
velocity before TOUCHING the FLOOR = u  m/s
   u² = 2 g h =  2 * 9.8m/s² * 40 m= 784
   u = - 28 m/s   downwards.

height of rebound = 10 m
velocity after touching the ground = v  m/s
 v² = 2 g h = 2* 9.8 * 10 = 196 
 v = 14 m/s

Impulse is equal to the change in linear momentum during the impact/collision
     = m v - m u  = 100 /1000 kg * (14 - (-28)) = 4.2 kg-m/s  or N-sec

AVerage force during the impact = 4.2 N-sec/0.2 sec = 21 Newtons.

We KNOW that,
v=fλ
3X 10⁸ms⁻¹=f X 1000m
f=3X10⁵Hz

Objects which allow only some PART of a INCIDENT LIGHT are called translucent objects. 
eg BUTTER paper,oil paper

Mixing characteristics of one 2s orbital and 3 2p orbital are KNOWN as SP3 hybridisationExample methane

Myopia is ALSO known as shortsightedness means person can see near things CLEAR but CANT focus on FAR objects well.Hence concave lens are used to correct this defect of vision .In this the image is not focussed on RETINA but it is formed in front of it.

Heya!!

Here is your answer.

Q-

Ans:-The electric resistance of a material is the MEASURE of hindrance it creates to the flow of electric current.

Read the following points to understand it better.

✨The magnitude of the current produced depends on its resistance.

✨The lower the resistance, the greater is the current.

✨Materials like metals have a very low resistance.So they conduct electricity well and are called good conductors or simply, conductors.

✨ Materials like wood, plastics, runner and mica conduct almost no electricity.They are called BAD conductors or insulators.They have a very high resistance.

✨There is no material which has no resistance.But, there are many materials like coal which have very low resistance.

✨ Resistance does not only depend only on materials. It also depends on the thickness and length of the material used.

✨A thin WIRE has HIGHER resistance than a THICK wire and a long wire has a higher resistance than a short wire.

Q-

Ans:-We measure electrical resistance in OHMS.

Q-

Ans:- We measure the resistance of a material by an instrument called the ohmmeter.

⭐ Hope you understood ⭐

Speed of SOUND = 300 m/s
distance TRAVELLED in 5 second = 300×5 = 1500m
distance travelled in 6 second = 300×6 = 1800m

If they are on OPPOSITE SIDE of the source, the distance will be maximum
D = 1500+1800 = 3300m 

If they are on same side of the source, the distance will be minimum
D = 1800-1500 = 300m

So maximum distance is 3300m and minimum distance is 300m.

the concave mirror of focal length will form erect and magnified image when KEPT between focus and pole ( it COULD be at a DISTANCE of 5 cm ,10cm ETC till 15 from the pole)

to OBTAIN inverted image, an object can be placed at focus( 15 cm from pole) or between focus and centre of curvature( at 16, 20 etc cm till 30) or at centre  of curvature ( at 15 cm from pole)  or beyond centre of curvature (more than 15cm from pole) or at infinity

so a concave mirror can form erect as well as inverted image of an object

U = -50 cm
m = -1



Since v= -50cm, the image is formed exactly at the same position as OBJECT. so the DISTANCE between them is 0. or mathematically, distance between image and object is GIVEN by

v - u = -50 - (-50) = -50 + 50 = 0

speed = 144km/h
          = 144*5/18 = 40m/s
apply
V = u + at
v = 40m/s
u = 0m/s
a = ?
t = 20 s
40 = 0 + 20*a
a = 2m/s²
apply
s = UT  + at²/2
s = ?
u = 0m/s
a = 2m/s²
t = 20s
s = 0 + 2*20²/2
s = 400m
hence CAR covers 400 meter.

Electric POWER is the RATE of energy CONSUMPTION in an electric circuit.The electric power is measured in units of watts

Power of heater(P) = 2kW
Specific HEAT of water (c)= 4.186 kJ/kg
mass of water (m)= 20 kg
temperature change (ΔT)= 10°C to 30°C
let the time taken = t second

As all energy is taken up by the water, we just NEED to equate the amount of heat released by water in t seconds to the amount of heat required to raise the temperature from 10°C to 30°C. Thus

A) The WEIGHT of the water displaced INCREASES (To balance the additional weight of the boy, the boat sinks sinks deeper, displacing more liquid and thus increasing the BUOYANT force according to ARCHIMEDES rule)
b) The buoyant force increases due to increase in the weight of the liquid displaced (according to archimedes principle).

1 pascal is the pressure exerted or experienced by a body or OBJECT when a thrust of 1 N acts on an area of 1 metre.sq.

Mass of boy = 40 kg 
Weight of Boy= 40 × g
                     = 40 × 10 = 400 N
Area = 0.04m.sq
 
Pressure = Force/Area
              = 400/0.04
              = 400 × 100 / 4
              = 100 × 100 
              = 10000 PA

A.


Since the frequency is ultrasonic, it can't be HEARD by humans.

b. Sound travels faster in solids than gases. So when we put our ear on railway track, we can hear the sound of approaching TRAIN through the steel track. The sound wave travelling through air takes very LONG time to reach US as it travels at much lower speed. Sometimes it doesn't reach us and we can't hear the sound as the energy in the wave is DISSIPATED in the air.

If two MIRRORS are placed at an angle Ф, NUMBER of images would be 



For the two adjacent mirrors on walls,


For one mirror on wall and other on CEILING,


For another mirror on wall and other on ceiling,


Total images = 3+3+3 = 9 images.

Radioactivity was DISCOVERED by becquerel which was serendipity in 1986.He OBSERVED a peuliar PROPERTY of uranium salt affecting photographic plate EVEN though when plate was packed  in a light PROOF  package.

H=440 j
p=11 w
p=h/t
  11 =440/t
11t=440
t=440/11
t=40 S