67486 + Interview Questions in Secondary School in Physics

1.	I want reading of the investigatory project of calss 12 on minimum deviation by prism
Answer» I HOPE this is what you wanted.. tr no angle of incidence deflection 1 35 45 2 40 46 3 45 38 4 50 40 5 55 43 after plotting the graph, you will get the angle of MINIMUM deviation to be 38 degrees *note that all values are in degrees

Discussion

2.	Which observation is correct & why?s.no1 30 19 292 40 28 403 50 36 504 60 40 59
Answer» 2nd ONE is CORRECT because if u apply SNELLS law, u'L get the refractive INDEX as 1.5

Discussion

3.	Circle the odd one out and give reson for your choice aluminium,iron,copper,bismuth,nickel
Answer» The ODD ONE is Bismuth . Because its an RADIOACTIVE element and OTHERS are not

Discussion

4.	A heat engine (efficiency=40%) does 20 kJ of mechanical work. How much is the heat supplied to this engine in calories?
Answer» EFFICIENCY = 40% $\eta= \frac{work\ done}{<klux>HEAT</klux>\ <klux>SUPPLIED</klux>}\\ \\ \Rightarrow 0.4= \frac{20\ kJ}{Heat\ supplied} \\ \\ \Rightarrow Heat\ Supplied= \frac{20}{0.4} =50\ kJ$ $1\ calorie = 4.184\ J\\50 kJ = \frac{50}{4.184}\ <klux>KCAL</klux>=11.95\ kcal$ So 11.95 kcal heat should be supplied.

Discussion

5.	Y diesel engine is efficient than petrol engine ???
Answer» The efficiency of an engine is determined from its COMPRESSION RATIO. Compression ratio is the ratio of the maximum volume of the combustion CHAMBER to its minimum volume. The more the compression ratio, the more is the efficiency. SINCE diesel engine OPERATES at higher compression ratio than petrol engine, it has higher efficiency.

Discussion

6.	Explain presbyopia ???????????
Answer» Its nothing more than a problem associated with eye lens and eye sight as we age up. don't you know that our old aged grand parents find it very difficult to read and see, the main reason behind it is PRESBYOPIA. the crystalline lens of your eye loses its FLEXIBILITY. as you get old your lens can no longer change shape and so cannot see close objects and this condition is presbyopia. P.S: speciality of our lens is that it can change shape ACCORDING to focus on distant or nearer objects-short words power of accommodation. you'll LOSE it in the case of presbyopia.

Discussion

7.	Why is sun colour is red while sunrise and sunset
Answer» During sunrise n sunset, when the sun is at horizon, the distance of sun from EARTH is MUCH........therefore the light rays coming from sun with low wavelengths scatter VRY far from the earth n red light which has the highest wavelength experiences least scattering n TRAVELLS a LARGE distance and as a result, reaches our eyes n we see the sun red.

Discussion

8.	Why is sky is blue ???????????
Answer» Blue COLOUR has very less wavelength as a result it scatters the most..n sky APPEARS blue..From the relation Is= 1/wavelength^4 where Is means SCATTERING of LIGHT .

Discussion

9.	What is kirchoff's second law?
Answer» Kirchoff's second LAW (voltage law) Kirchoff's voltage law states that the algebraic sum of the products of resistance and current in each part of any closed circuit is equal to the algebraic sum of the EMF's in that closed circuit. This law is a CONSEQUENCE of conservation of ENERGY.

Discussion

10.	1.A truck weighing 1000kgf changes its speed from 36km/hr to 72 km/hr in 2 mins. calculate:i) the work done by the engine .ii) its power.2. A body of mass 60kg has the momentum 3000kg m/s. Calculate:i) the kinetic energy.ii) the speed of the body
Answer» 1. mass of truck = 1000 kg u = 36 km/h = 10 m/s v = 72 km/h = 20 m/s time = 2 min = 260 = 120 s acceleration = (v-u)/t = (20-10)/120 = 1/12 m/s² force = ma = 1000(1/12) = 1000/12 N s=(v²-u²)/2G = (400-100)/210 = 15m Work DONE = Fs = (1000/12)15 = 1250 J Power = W/t = 1250/120 = 104.1 J/s 2. mass = 60kg momentum = 3000 kgm/s KE = p²/2m = 3000²/(2*60) = 75000 J = 75 kJ velocity = p/m = 3000/60 = 50 m/s

Discussion

11.	What is ultrasonic sound ? with examples ? how much Hz can be a human child (infant) hears ?
Answer» ultrasonic SOUND - sound of frequency of more than 20000 Hz which cannot be heard by HUMAN ears . but a human child infant can HEAR UPTO 25000Hz and animals can be hear more than 20000 Hz . e.g. dogs ( upto 50000 Hz ) , cats , bats ,ETC.

Discussion

12.	Derive for parallel connection equivalent resistance(r) = \frac{R1*R2}{R1+R2}
Answer» SEE let there be n resistors of resistance r1,r2,r3 ...... rn so in parallel connection the potential difference remains same but the current spreads in different resisters in i1,i2,i3 ...... in so let the total potential difference be V current be I and equivalent resistance be R so using junction rule I = i1 + i2 + i3 + . . . + in so we KNOW I = $\frac{V}{R}$ from OHM's Law so $\frac{V}{R}= \frac{V}{r1}+\frac{V}{r2}+\frac{V}{r3}+....+\frac{V}{rn}$ cancelling V from both sides we GET $\frac{1}{R}= \frac{1}{r1}+\frac{1}{r2}+\frac{1}{r3}+....+\frac{1}{rn}$ *PROVED*

Discussion

13.	How much velocity we need to escape black hole?
Answer» If we use CERTAIN equations, they tell us that if we go in a black hole it will take INFINITE time to get out! hence we can never get out of a black hole! SOO noooooo velocity can ever beat a black hole! not EVEN LIGHTS velocity!

Discussion

14.	I want to know about prism
Answer» Prism is a 3D substance which have THREE triangular faces and two rectangular faces . It HELPS in the DISPERSION of light

Discussion

15.	Speech about science in our future
Answer» Now, TECHNOLOGY hasbecome a very IMPORTANT part of our lives nowadays. During the past few years,technology has EVOLVED in MANY ways and is probably without a doubt better thanever before. People are always trying to find something new that will improveour lives dramatically. Some of the creations that have really CHANGED ourlives are the computer, telephone, internet and electronic mail, television,cell phone and voice mail.Today, There is no work which cannot be done withoutthe assistance of machines and there is not a single area of human activitywhere machines don’t have to be used. No one can deny the fact that gadgetshave not only simplified our lives but also made them more comfortable andluxurious. but i think in future, we will be in mars. i think every personcan get a rocket at cheap rates to have a visit on earth like a tour.

Discussion

16.	What do you mean by sea breeze and land breeze?
Answer» SEA BREEZE- during the day the land gets heated faster than the water . the air over the land becomes HOTTER and rise up . the cooler air from the sea rushes in towards the land to take its place the WARM air from the land moves towards the sea to complete the cycle. the air from the sea is called sea breeze. LAND BREEZE- at night it is EXACTLY the REVERSE the water cools down more slowly than the land so the cool air from the land moves towards the sea this called as land breeze. THANKU.. HOPE IT HELPS

Discussion

17.	Sound can travel in a straight line
Answer» No.Sound does not travel in a straight line.It travels in the FORM of waves that are ACCOMPANIED by compressions and rarefractions.

Discussion

18.	If 4^x-4^x-1=24 then [2*x]^x =
Answer» $4^x-4^{-x}=24\\ \\4^x- \frac{1}{4^x} =24\\ \\ let\ 4^x=t\\ \\t- \frac{1}{t}=24\\ \Rightarrow t^2-1=24t\\ \Rightarrow t^2-24t-1=0\\ \Rightarrow t=12+ \sqrt{145}\\ (t=12- \sqrt{145}\ is\ ignored\ as\ 4^x\ can't\ be\ negative )\\ \\thus\ 4^x=12+ \sqrt{145} \\2^x= \sqrt{4^x} = \sqrt{12+ \sqrt{145}}$

Discussion

19.	1.A wave of frequency 1200 Hz spred over a lenth of 10 m.Wat is the wavelength?what is the speed?2.A constant force of magnitude 10 N is applied on a 20 kg particle for 2s.Wat is acceleration of the paticle.If the particle starts from rest wat is its final velocity?
Answer» We KNOW that VELOCITY = WAVELENGTH ( distance ) * FREQUENCY... putting the VALUES... v=120010v=12000m/s 2 F=10 M=20t=2 F=ma ...10=20aa=0.5m/s^2 by using v=u+at...calculate the final velocity!

Discussion

20.	what do you understand by near point of the human eye? what is the least distance of distinct vision?
Answer» The least distance at which our EYE can see without any strain or pressure is CALLED the NEAR point of our eye.The least distance of distinct vision is 25 cm

Discussion

21.	What is the importance of penstock in a dam
Answer» Penstocks are ALSO used in MINE tailings dam construction. The penstock is usually situated fairly close to the CENTER of the tailings dam and built up using penstock RINGS. These control the water level, letting the slimes settle out of the water. This water is then PIPED under the tailings dam back to the plant via a penstock pipeline.

Discussion

22.	What is the nature of clocks used in spaceships?
Answer» They are not exactly like clocks on the earth ,they are somewhat like clocks inside the computers which keep track of time...........It is very MUCH necessary for the astraunauts the astraunaut to keep track of time...bcoz in space COMMUNICATION there is a GAP of 40 min round trip light time

Discussion

23.	A person standing near a railway line hears two distinct sounds of a train between time interval 2s.how much is the distance of the train?Velocity of steel=16 times velocity of air{340 m/s}
Answer» If the person standing near a RAILWAY line hears two DISTINCT sounds of a train, then the sounds are - one travelling through steel and the another travelling through air. Let the distance of train be d from the person. speed of SOUND in air = 340 m/s speed of sound in steel = 340 × 16 = 5440 m/s time taken by sound travelling through steel to reach the person = $t_s$ time taken by sound travelling through air to reach the person = $t_a$ $time= \frac{distance}{speed}\\ \\ t_s= \frac{d}{5440} \\ \\t_a= \frac{d}{340}$ GIVEN that $t_a - t_s=2$ $\frac{d}{340}-\frac{d}{5440}=2\\ \\d( \frac{1}{340} - \frac{1}{5440} )=2\\ \\d(\frac{16-1}{5440})=2\\ \\d=\frac{25440}{15}=725.33\ m$ Distance of train is 725.33 m.*

Discussion

24.	Why do dogs pant in summer use a concept of evaporation?
Answer» Dogs do not have sweat glands like human being. They pant becauses the saliva evapprates, it cools them Evaporation takes into CHEMICAL REACTION in point of view in when atoms goes to a higher ENERGY level, they will break into bonds during when this OCCURS, the BREAKING of bonds will release energy thus cooling dog .It is very, high in hot summer days because of high evaporation.

Discussion

25.	What is the orbit velocity of jupiter ?
Answer» *13 m/s is a VELOCITY of JUPITER .*

Discussion

26.	Does the temperature of water rise continuously if heat is supplied to it
Answer» 1) the temperature of water does not rise continuously if heat is supplied to it. 2) when it reaches its BOILING point (100 deg celcius) the temperature remains CONSTANT for some time. 3) because the supplied heat ENERGY will be used for breaking bonds and impurities present in it. 4) after this, the PHASE changes (may be from ice to water or from water to vapour.)

26.

Does the temperature of water rise continuously if heat is supplied to it

Answer»

1) the temperature of water does not rise continuously if heat is supplied to it.

2) when it reaches its BOILING point (100 deg celcius) the temperature remains CONSTANT for some time.

3) because the supplied heat ENERGY will be used for breaking bonds and impurities present in it.

4) after this, the PHASE changes (may be from ice to water or from water to vapour.)

Discussion

27.	Woollen clothes does not allow body temperature to decrease. What is the reason how could we appreciate this
Answer» 1) woollen yarn CONTAINS a large amount of air trapped ,so it does not allow our body heat to flow out. 2)woollen yarn is a bad conductor of of heat,so it does not allow the body heat to flow forward. 3) woollen yarn has high SPECIFIC heat so,it does not allow the body heat to flow out quickly 4) because of the above REASONS ,woollen does not decrease our body TEMPERATURE.

27.

Woollen clothes does not allow body temperature to decrease. What is the reason how could we appreciate this

Answer»

1) woollen yarn CONTAINS a large amount of air trapped ,so it does not allow our body heat to flow out.

2)woollen yarn is a bad conductor of of heat,so it does not allow the body heat to flow forward.

3) woollen yarn has high SPECIFIC heat so,it does not allow the body heat to flow out quickly

4) because of the above REASONS ,woollen does not decrease our body TEMPERATURE.

Discussion

28.	Find the heat needed to convert 10g of ice at 0 celsius to water at 20 celsius.Given: Latent heat of fusion of ice= j/kg; specific heat of water= 4200 J/kg-k.
Answer» 10g=0.01kgFor converting 0 DEGREES ice to 0 DEGREE water the amount of heat isQ=mlf=0.01336000=3360For converting 0 degrees water to 20 degrees water isQ=massSPECIFIC heatTEMPARATURE difference=0.014200*(20-0)=840Total heat =3360+840=4200

Discussion

29.	1Q.Why does a bulb glow immediately irrespective of the connecting wire ,when we switch on?2Q.why doesn't a bird get shock when it stands on a high voltage wire?
Answer» when we switch on any electric circuit, irrespective of the length of the conductor an electric FIELD is set up throughout the conductor INSTANTANEOUSLY due to the VOLTAGE of the source connected to the circuit. this electric field makes all the electrons to move in a specified direction SIMULTANEOUSLY , hence the bulb GLOWS.

Discussion

30.	Which glass has high pitched sound the one with more water or the one with less water
Answer» The GLASS with LESS WATER because its FREQUENCY will be HIGH.....

Discussion

31.	Which energy is needed for heating up water?
Answer» HEAT ENERGY is NEEDED in HEATING up WATER

Discussion

32.	Why birds chirps before the occurrance of an earthquake
Answer» Birds have the POWER of sensing LOW frecquency waves and pressure CHANGES so they try to escape from the danger to warn its fellow beings birds generally do chirpp as other beings LIKE HUMANS dont have such power . its just like why do you shout when you see a house on fire

Discussion

33.	A child of mass 35kg is sitting on a trolley of mass 5kg.the trolley is given a push by applyinga force so that it begins to move with a speed of 4 m/s.the trollye comes to rest after covering a distance of 16m find1) work done on the trolley2) work done by the trolley before coming to rest
Answer» TOTAL mass of system=35+5=40kg initial velocity(U)=4m/s distance COVERED(s)=16m final velocity(V)=0m/s work DONE by trolley=v²-u²=2as 16=2a×16 a=1/2 f=m×a f=40×1/2 =20N w=f×s=20×16 =320J

Discussion

34.	Frame 5 questions and answers on stars and solar system
Answer» 1) Which is the centre of our solar system? ANS) Sun 2)Which is the HOTTEST PLANET in the solar system? Ans) Venus 3) Which is the largest canyon in the solar system.How big is it? Ans) Vallas Marinaris is the biggest canyon in the solar system and is about 3000 MILES long. 4)Name the planet which rotates on its side? Ans) Uranus 5) How many moons does Mars have? Ans) Two , they're Phobos and Diemos.

Discussion

35.	Hots on stars and the solar system
Answer» 1. If We Are In Space We Have To Drop ONE Pencil And A Big IRON Ball On The Moon Which Substance FALL On The Moon First?2 . Why venus is HOTTER than mercury as it is far away from the sun as mercury?3 . What do you mean by GOD particle?4 . How is gravity formed?5 . Do Sun has an orbit?

Discussion

36.	How do you appreciate the technology in making ships float?
Answer» Mr.Archimedes had made the LAW of floatation and DIE is WAT had and RATHER has helped the MODERN theory of floatation of ships and boats

Discussion

37.	The frequency of emf generated by a generator depends upon its
Answer» A)its SPEED B) no. Of POLES

Discussion

38.	What scalar or vector point function
Answer» A scalar function is a function that ASSIGNS a REAL number (i.e. a scalar) to a set of real variables. Its general form isu = u(X1, x2, ... , xn)where x1, x2, ... , xn are real numbers.A VECTOR function is a function that assigns a vector to a set of real variables. Its general form is F = F1(x1, x2, ... , xn) i + f2(x1, x2, ... , xn) j + f3(x1, x2, ... , xn) kwhere x1, x2, ... , xn are real numbers.

Discussion

39.	If the force of attraction between the earth and a body of mass 'm' is 9 * 10^7 ,what would be the value of mass' m ' ? given G= 7.6 * 10^-11 Nm^2/Kg^2 , radius of the earth , R = 6.4 * 10^6 m , mass of the earth = 6.4 * 10^24 Kg. .... plzzz helpppppppp ......
Answer» Given , force of gravitation ( F ) = 9 * 10^7 N MASS of the earth = 6 * 10^ 22 kg G = 6.7 * 10^-11 Nm^2 per kg R = 6.4 * 10^6m , m = ? $F = G \frac{M * m}{r^2 } m = \frac{FR/G M} m = 9 * 10 ^7 * (6.4 * 10^6)^2 / 6.7 * 10^-11 * 6 * 10^22 m = 9.17 * 10^6 kg$

Discussion

40.	By using a slinky,what type of wave is produced?Plzzzzzz answer ......... itzzzzz very urgent....
Answer» By using a slinky,both longitudinal and transverse waves can be produced. Hold one end of the Slinky still on the floor. While holding the slinky on the floor, MOVE the other end of the Slinky, in a SINGLE motion, back andforth very quickly perpendicular to its stretchedlength. A transverse WAVE will be MADE. Hold one end of the Slinky still. Pull the other end of the STRETCHED metal Slinky andthen let go of the coils. A longitudinal wave will be made and will travel back and forthover the length of the Slinky.

Discussion

41.	A cricket ball of mass 150g is moving with a velocity of 12m/s and hitted by a bat so that the ball is turned back with a velocity of 20m/s. if the duration of contact btw the ball and bat is 0.01s.then:1. the impulse is----------------------
Answer» <P>The impulse of the ball is 4.8 Ns. Given data: Initially, velocity of the ball = 12 m/s Final velocity = 20 m/s Mass, m = 150 g = 0.15 kg To find: Impulse = ? SOLUTION: $\text {Impulse} =F \Delta t$ We KNOW that, $F=\frac{\Delta p}{\Delta t}$ Where, p is momentum Therefore, $\therefore \text {Impulse}=\frac{\Delta p}{\Delta t} \times \Delta t$ $\Rightarrow \text {Impluse}=\Delta p$ $\Delta p=m v_{2}-m v_{1}=m\left(v_{1}-v_{2}\right)$ $\Delta p=0.15 \times(-20-12)$ Since, the "rebound velocity" is taken negative in MOTION as the direction is changed. Thus, Impulse = 4.8 Ns

41.

A cricket ball of mass 150g is moving with a velocity of 12m/s and hitted by a bat so that the ball is turned back with a velocity of 20m/s. if the duration of contact btw the ball and bat is 0.01s.then:1. the impulse is----------------------

Answer»

<P>The impulse of the ball is 4.8 Ns.

Given data:

Initially, velocity of the ball = 12 m/s

Final velocity = 20 m/s

Mass, m = 150 g = 0.15 kg

To find:

Impulse = ?

SOLUTION:

$\text {Impulse} =F \Delta t$

We KNOW that,

$F=\frac{\Delta p}{\Delta t}$

Where,

p is momentum

Therefore,

$\therefore \text {Impulse}=\frac{\Delta p}{\Delta t} \times \Delta t$

$\Rightarrow \text {Impluse}=\Delta p$

$\Delta p=m v_{2}-m v_{1}=m\left(v_{1}-v_{2}\right)$

$\Delta p=0.15 \times(-20-12)$

Since, the "rebound velocity" is taken negative in MOTION as the direction is changed.

Thus,

Impulse = 4.8 Ns

Discussion

42.	I need 20 points about magnets
Answer» Hammering or heating a magnet in a hot flame will cause it to loose its magnetic PROPERTIES. In both scenarios the MOLECULES lose their north-south alignment and get arranged in random directions.All magnets have a north and south pole, including all of our custom promotional magnets. Opposite poles attract while the same poles repel each other.Many scientists believe the Earth's magnetic field helps to guide migrating birds.Over 80% off all households in the US have promotional magnets on their refrigerator.The worlds largest magnet is planet Earth. Earths hot liquid core contains iron which, as it moves, creates an electric current that generates a magnetic field around the planet.Neodymium magnets (a type of very strong rare-earth magnets) are known to repel sharks. While we don't currently sell neodymium magnets we do have a large collection of SUPER strong magnets.Today's high speed trains use magnets to float each car, reducing friction and allowing the train to run very efficiently.Magnets can be found in many common household items such as telephones, computers, stereos, refrigerators, TVs, and VCRs.A coil of wire with an electric current flowing through it becomes magnetized.The pull of a magnet is strongest at the north and south pole.Rare-earth magnets are the strongest type of permanent magnets made.Legend has it that magnets were first discovered around 4,000 years ago when a shepherd named Magnes got the nails in the sole of his shoe stuck to a magnetic rock, later called magnetite.Magnets are usually made of steel or iron. Special alloys of iron, nickel, copper, COBALT, and aluminum can also be made into magnets.Earth, Saturn, JUPITER, Neptune, and Uranus are the only planets in our solar system with magnetic fields.

Discussion

43.	3 equal charges which has magnitude of 2×10^6 coulomb is placed at the corners of right angled triangle of sides 3, 4, 5find the force on the charge at right angle corner.
Answer» See the diagram. the force acting on charge at B due to charge at A is $F_1= \frac{1}{4 \pi \epsilon_0} \frac{q_1q_2}{r^2} =910^9 \frac{(210^6)^2}{4^2}=2.2510^{21}N$ It ACTS in the DIRECTION from A to B. the force acting on charge at B due to charge at C is $F_2= \frac{1}{4 \pi \epsilon_0} \frac{q_1q_2}{r^2} =910^9 \frac{(210^6)^2}{3^2}=410^{21}N$ It acts in the direction from C to B. Since F₁ and F₂ are at right angles to each other, the RESULTANT F is given by $F= \sqrt{F_1^2+F_2^2}\\F = \sqrt{(2.2510^{21})^2+(410^{21})^2} \\F= \sqrt{21.062510^{42}} \\F=\boxed{4.5910^{21}\ N}$

Discussion

44.	What is the mass and radius of saturn , sun , earth and moon .
Answer» *mass and RADIUS :-* **SATURN mass - 6 10^26 Kg* radius - 6 10^7 m* SUN mass - 2 10^30 Kg* radius - 7 & 10^8 m EARTH mass - 6 10^24* radius - 6400 KM MOON mass - 7.3 10^22 kg* radius - 1740 km**

Discussion

45.	a ball of mass 200 g falls from a height of 2.0 m . what is the kinetic energy of the ball when it reaches the ground ? take g = 9.8 m/s^2
Answer» **m = 200 G = 200/1000 kg = 200 10^-3* H = 2 m g = 9.8 m/s to calculate k.e. of the ball reaches the ground = ? P.E. at the top = P.E. at the ground = MGH = ( 200 10^-3 )9.8 * 2* = 3.92 joules therefore , K.E. of the ball when it reaches the ground is same as P.E. at the top => 3.92 J**

Discussion

46.	A flow chart on air pollution and health impacts of air pollution
Answer» Global Climate ⇒ REGIONAL Climate ⇒ Public HEALTH Impacts ⇔ AIR Quality ⇔ Land use/Land cover ⇒ Air Quality

Discussion

47.	on what actors does the amount of refraction caused by a passage of light ray trougha prism depend upon?
Answer» It DEPENDS on the MEDIUMS.

Discussion

48.	Optical fibre works on the
Answer» Optical FIBRE works on the PRINCIPLE of total internal REFLECTION.

Discussion

49.	Light from the star, Alpha Centauri, which is nearest to the earth after the sun, reaches the earth in
Answer» LIGHT from the star, Alpha Centauri, which is nearest to the EARTH after the SUN, REACHES the earth in 4.37 years.

Discussion

50.	Nuclear sizes are expressed in a unit named
Answer» NUCLEAR SIZES are EXPRESSED in a unit named Angstrom. It is written as Å. 1 Å = $10^{-10}\ m$

Discussion

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Which glass has high pitched sound the one with more water or the one with less water

Which energy is needed for heating up water?

Why birds chirps before the occurrance of an earthquake

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Frame 5 questions and answers on stars and solar system

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If the force of attraction between the earth and a body of mass 'm' is 9 * 10^7 ,what would be the value of mass' m ' ? given G= 7.6 * 10^-11 Nm^2/Kg^2 , radius of the earth , R = 6.4 * 10^6 m , mass of the earth = 6.4 * 10^24 Kg. .... plzzz helpppppppp ......

By using a slinky,what type of wave is produced?Plzzzzzz answer ......... itzzzzz very urgent....

A cricket ball of mass 150g is moving with a velocity of 12m/s and hitted by a bat so that the ball is turned back with a velocity of 20m/s. if the duration of contact btw the ball and bat is 0.01s.then:1. the impulse is----------------------

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on what actors does the amount of refraction caused by a passage of light ray trougha prism depend upon?

Optical fibre works on the

Light from the star, Alpha Centauri, which is nearest to the earth after the sun, reaches the earth in

Nuclear sizes are expressed in a unit named