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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 901. |
Find out reasons for the situations Accidents that happen to passengers who do not wear seat belts are more fatal. |
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| 902. |
According to the third law of motion when push on an object , the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the road side, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on their logic and explain why the truck does not move . |
| Answer» Solution :The logic is the ACTION and REACTION always act on different bodies, so they cannot cancel each other. When we push a massive truck, the force of FRICTION between its tyres and the road is very large and so that truck does not MOVE . | |
| 904. |
A boy of mass 50 kg runs up a staircase of 45 steps in 9 s. If the height of each step in 15 cm, find his power. Take g=10ms^(-2). |
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Answer» Solution :Weight of the BOY `mg=50kgxx10ms^(-2)` `=500N` HEIGHT of the staircase `h=45x(15)/(100)m=6.75m` Time taken to CLIMB `t=9S` Power `P=("Work done ")/("Time taken")` `=(mgh)/(t)` `=(500Nxx6.75m)/(9s)=375W` Power is 375. |
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| 905. |
At 20^(@)C, the minimum distance of a person from a sound reflecting surface to hear an echo is: |
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Answer» 12.2m |
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| 906. |
Arrange the following steps in a sequential order to verify the laws of reflection. (A) A hard , smooth surface (AB) is mounted vertically overa horizontal board on which two tubes P and Q , point towards the surface AB. (B) The tube Q is adjusted such that the listener would be able to hear the ticking sound clearly at the end away from AB. (C) The sound waves from a source , like ticking clock are directed to the surface AB through the pipe P inclined at an angle to AB . (D) By measuring the angles the tubes make with the surface AB , the laws of reflection are verified . |
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Answer» <P>ABCD |
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| 908. |
While performing an experiment on verifying the laws of reflection of sound, a students is to choose between (i) a narrow or a wide tube, and (ii) is strong or a faint source of sound. The observed experimental difference, between the values of angle of incidence and angle of reflection, is likely to be minimum when he chooses a: |
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Answer» NARROW TUBE and a FAINT source |
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| 909. |
Four students A, B, C and D while performing an experiment on establishing the relation between the loss of weight of a small solid when fully immersed In tap water and the weight of water displaced by it, used four different shapes of overflow-cans containing water The arrangement, the would give correct results, is that of student: |
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Answer» A |
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| 910. |
Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times takes by the sound wave in air and in aluminum to reach the second child. |
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Answer» Velocity of sound WAVE w in aluminium`=6420` m/s Let LENGTH of rod be 1 Time TAKEN for sound wave in air `t_(1)=1//`velocity in air Time taken for sound wave in aluminium, `T_(2)=1//`velocity in a aluminium. THEREFORE, `t_(1)//t_(2)=` velocity in aluminium/velocity in air `=6420//346=18.55:1` |
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| 911. |
The anode in electrolyte is negative. |
| Answer» SOLUTION :FALSE Correct STATEMENT : The ANODE in ELECTROLYTE is positive. | |
| 912. |
Velocity-time graph for a body moving with retardation is shown. Calculate the (i) retardation and (ii) displacement of the body. |
Answer» Solution : (i) Here, retardation=`("Decrease in VELOCITY")/("TIME taken")` `=((10-0)m//s)/((5-0)s)=(10)/(5)m//s^(2)=2m//s^(2)` (ii) Displacement=Area of velocity-time graph =Area of `DeltaAOB` `=(1)/(2)xxOBxxOA=((1)/(2)xx5xx10)m=25`m. |
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| 913. |
Name the physical quantities which are measured in the following unit ly |
| Answer» SOLUTION :DISTANCE (or LENGTH) | |
| 914. |
Which one of the following statements about power stations is not true ? |
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Answer» HYDROELECTRIC POWER stations use water to drive TURBINES |
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| 915. |
Define electric current and give its unit. |
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Answer» Solution :CURRENT is the rate of which charges flow past a POINT on a CIRCUIT. Current (I) is represented as, `I=q"/"t` The standard SI unit for current is ampere with the symbol A. |
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| 916. |
What is the kinetic energy of an object? |
| Answer» Solution :The energy possessed by an OBJECT DUE to its motion is called its KINETIC energy. | |
| 917. |
Which device is used to measure the relative density of a liquid? |
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| 919. |
Why are roads on mountains inclined in wards at terms ? |
| Answer» Solution :A vehiclemoving on mountains is in the inertia of motion. At a sudden TURN there is a TENDENCY of vehicle to fall of the road due to sudden change in the line of motion HENCE the ROADS are inclined inwards so that the vehicle does not fall down THEMOUNTAIN. | |
| 920. |
Thedivisionson themainscaleof a screw gaugeare1 mmapartand thescrewof thespindleadvances by 5mainscaledivisions when thespindleis given5 completerotations. Howmanydivisionsare tobeprovided on thecircular scalefor theleastcountof theinstrument is tobe 1 mu m ? Whatchanges arerequied of thenumberif divisionscan beonly500for thesame leastcount? |
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Answer» Solution : Leastcount = `(1 MSD)/(N)` `=(0.5 mm)/(10) =0.05 mm` Diameter =x +1Y 9.75 mm =(x+0.05y) mm =x+ 0.05 y Sincey `lt ` 10 and0.05y `lt`0.5. 9.75can be written as 9.5 + 0.25 (9.5 mm) +(0.25 mm) = (xxmm )+(0.05 y mm) SINCE 1 MSD=0.5mm The MSR`=(9.5)/(0.5) =10 " and " 0.05 y0.25` (b)9.75 =(x+ly) -0.35 =9.75 +0.35 =10.10 =10+ 0.1 x=10 =MSR`=(10)/(0.5) =20` 0.05 =0.1 `y= (0.1)/(0.05) =2 (=VCD)` MSR =20 ,VCD =2 |
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| 921. |
The relative density of gold is 19.3. The density of water is 103kg//m^(3) ? What is the density of gold is S.I unit ? |
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Answer» Solution :Relative DENSITY of GOLD =19.3 Relatvie density OG gold `=("Density of gold")/("Density of WATER")` Therefore Density of gold=Relative density of gold x Density water `=19.3xx10^(3)kg//m^(3)` `=19300kg//m^(3)` |
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| 922. |
What is a discharge tube? |
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| 923. |
Discuss whether the walls of your classroom are at rest or in motion. |
| Answer» SOLUTION :The walls of a classroom are at rest with RESPECT to nearby other BUILDINGS. | |
| 925. |
An iceberg floats on fresh water with a part of it outside the water surface. Calculate the fraction of the volume of the iceberg which is below the water surface. Given : density of ice =917kgm^(-3), density of fresh water =1000kgm^(-3) |
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Answer» Solution :By the PRINCIPLE of floatation `("VOLUME of iceberg IMMERSED")/("Total volume of iceberg")=("Density of ice")/("Density of FRESH water")` `917/1000=0.917` Thus 0.917th part of volume of iceberg will reamin below the water SURFACE. |
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| 926. |
Weight of an object in free fall is zero? Why. |
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| 927. |
Height of water dam in hydroelectric power station is 20m. How much water, in 1 second, should fall on turbine, so that 1 MW power is generated? (g=10ms^(-2)) |
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Answer» `5000kg` `g=10ms^(-2)` `therefore P=(W)/(t)=(mgh)/(t)` `therefore m=(Pxxt)/(gxxh)=(10^(6)XX1)/(10xx20)=5000kg` |
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| 928. |
(a) How do quadruples swin naturally with head on water? (b) Distinguish between density and specific gravity. |
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Answer» Solution :(a) In case of a QUADRUPLY, the front part of its body is lighter than the HINDER parts. (b) Specific GRAVITY (RELATIVE density) of a SUBSTANCE is the ratio of its density of the density of water at `4^@C`. Density of a substance`=`its specific gravity`xx1000(kg)/(m^3)`. |
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| 929. |
Two conductos of the same size, shape and material have the same capacitance. |
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| 930. |
The nuclei of atoms of all elements are made up of protons and neutrons. Then why do only a few of them show radioactivity ? |
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Answer» Solution :COMPARE the NUCLEUS of the RADIOACTIVE elements with other elements. Recall the DIFFERENT factors which effect the stability of a nucleus. |
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| 931. |
In which of the following cases of motions, the distance moved and the magnitude of displacement are equal? |
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Answer» If the car is MOVING on straight road |
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| 932. |
A person has a hearing range from 20Hz to 20Khz. What are the typical wave lengths of sound wave in air corresponding to these two frequen cies ? Take the speed of sound in air of 344ms^(-1) |
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Answer» Speed = wave LENGTH `xx` frequency `= lambdaxx UPSILON` Speed of sound in air `=344m//s` (i) For `upsilon=20Hz` `lambda_(1)=upsilon//v=344//20=17.2m` (ii) For `upsilon=20000` Hz `lambda_(2)=upsilon//upsilon=344//20000=0.172`m Hence, for humans, the wavelengthrange for hearing is 0.0172 m to 17.2 m |
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| 934. |
Explain a method to find the thickness of a hollow tea cup . |
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Answer» Solution :To find the thickness of a hollowtea CUP, (i)Determine the pitch , of the least count and zero error of the screw gauge . (a)Pitch of the screw `= ("Distance moved by the pitch")/("No. of rotations by Head SCALE")` (b)Least count (LC) = 0.01 m m (c)Zero error: Positive zero error (ZE) = + (n`xx` LC) m m = + (n`xx` 0.01) m m `:.`Zero correction (ZC) = - (n `xx` 0.01) m m NEGATIVE zero error (ZE) = - (100 -n)` xx` LC m m `:.`Zero correction (ZC) = (100 -n) `xx` LC m m (ii)Place the tea cup between the TWO studs. (iii)Rotate the head until the tea cup is held firmly but not tightly , with the help of ratchat . (iv)Note the reading of the pitch scale crossed by the head scale (PSR) and the head scale division that coincides with the pitch scale axis (HSC). (v)The thickness of the tea cup is given by PSR + CHSR (Corrected HSR) . Repeat the experiment for different positions of the tea cup . (vi)Tabulate the readings. (vii)The average of the last column reading GIVES the thickness of the tea cup . Thickness of the tea cup = ________m m 
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| 935. |
A train takes 3 h to travel from Agra to Delhi with a uniform speed of 65 km h^(-1)'. Find the distance between the two cities. |
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| 936. |
A 900 kg car moving at 10 ms^(-1)takes a turn around a circle with a radius of 25 m. Determine the acceleration and the net force acting upon the car. |
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Answer» Solution :When the car turns around circle, it EXPERIENCES centripetal ACCELERATION `a=upsilon_2/r` `a=(10)^2 / 25 =100/25 "" therefore a=4 ms^(-2)` Net force ACTING upon the car , F= m a = 900 x 4 = 3600 N |
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| 937. |
In which medium the speed of sound is more : humid air or dry air ? Give a reason to your answer. |
| Answer» SOLUTION : In HUMID air. Reason: DENSITY of air decreases with the increase of moisture and `V PROP 1/(SQRTP)` | |
| 938. |
The line joining the centre of gravity of a cuboid and the centre of the Earth will fall within the base of the body even after being disturbed by an external force. Then the body is said to be in _____. |
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Answer» neutral equilibrium |
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| 939. |
Radha is a student of class IX in a school in Ambala city in Haryana. Radha's father, Mr. Vijat Kumar, is the Deputy Commissioner of Police in Ambala zone. Radha's family including her father, mother and five year old brother Pulkit, were invited for the celebrations of Air Force Day at the Ambala Air Force Base. During these celebrations, the final item was a fly-past by the fighter jet planes of Indian Air Force. Suddenly there was a loud, explosive noise in the sky over the celebration venue. All the eyes turned up towards the sky. Everybody saw the Indian Air Force's fighter jet planes flying at tremendous speed in a special formation. All the people started clapping for this beautiful and daring fly-past by Indian Air Force pilots. The thunderous sound produced by the speeding fighter planes was so loud that all the birds sitting on the nearby trees flew away. Radha's brother Pulkit was already undergoing treatment for some ear ailment. So, Pulkit got too much pain in his ears due to this intolerable explossive sound. Pulkit was carrying two sharpened pencils with him at that time. He tried to put these pencils inside his ears to get relief from severe pain in the ears. Radha snatched the pencils from Pulkit and warned him not to do it again. Radha was carrying some cotton ear buds in her purse. So, she put cotton ear buds into the ears planes thoroughly. Everyone was praising Indian Air Force for putting up a great show. Jai Ho! (a) What term is used for the extremely loud burst of sound produced by extremely fast, low flying fighter jet planes? What can you say about the speed of fighter jet planes which produce loud bursts of sound (or explosive noise) when the fly? What special name is given to this speed? (c) A fighter jet is flying low at a speed of 1100 km/h. State whether it will produce extremely loud burst of sound or not. Give reason for your answer. (d) Why did Radha prevent Pulkit from putting sharpened pencils into his ears? (e) Why did Radha put cotton ear buds into Pulkit's ears? (f) Name one object which travels at a speed greater than that of fighter jet plane producing loud burst of sound. (g) What values are displayed by Radha in this episode? |
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Answer» Solution :(a) Sonic boom. (b) The fighter jet planes which produces loud bursts of sound (or explosive noise) like that of a thunder, are travelling at a speed faster than the speed of sound in air. The speed which is greater than the speed of sound in air is called 'suspersonic speed'. (c) A fighter jet FLYING low at a speed of 110km/h will not produce extremely loud burst of sound (or sonic boom) because this speed is less than the speed of sound in air (which is about 1200 km/h). (d) Radha PREVENTED Pulkit from putting sharpened pencils into his ears because sharp objects can tear the delicate ear drum. The tearing of ear drum ca make a person deaf. (e) Radha put cotton ear buds into Pulkit's ears to SOFTEN the effect to extremely loud sound waves emitted by supersonic fighter jet planes during sonic boom and reduce PAIN in his ears. (f) Rocket. (g) The various values displayed by Radha in this episode are (i) AWARENESS of the delicate nature of human ear (ii) Desire to prevent damage to the ear drum of her brother (by preventing him from putting pencils into ears), and (iii) Reduce the suffering of her brother (by putting cotton ear buds into his ears). |
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| 940. |
What is buoyancy? How is buoyancy measured? |
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| 942. |
Name the instrument which can measure accurately the following the internal diameter of the neck of a water bottle |
| Answer» SOLUTION :VERNIER CALLIPERS | |
| 943. |
What is the time period of satellite near the earth's surface? (neglect height of the orbit of satellite from the surface of the earth)? |
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Answer» Solution :The force on the satellite due to earth is given by `F=(GmM)/(R^(2))` M-Mass of earth `=6xx10^(24) kg` m-mass of satellite, R-radius of earth `=6.4xx10^(6) m` Let V be the speed of the satellite `v=(2pi R)/(T) rArr T=(2 pi R)/(v)` REQUIRED centripetal force is PROVIDED to satellite by the gravitational force hence `F_(C )=(mv^(2))/(R)` But `F_(C)=(GMm)/(R^(2))` according to Newton.s law of gravitation. i.e., `(GMm)/(R^(2))=(m(2pi R)^(2))/(T^(2)R)` `rArr T^(2) =(4 pi^(2) R^(3))/(GM)`, as mass of the earth (M) and G are constants the value of T depends only on the radius of the earth. `rArr T^(2) alpha R^(3)` Substituting the values of M, R and G in above equation we get, T = 84.75 MINUTES. Thus the satellite revolving around the earth in a circular path near to the earth.s surface takes 1Hour and 24.7 minutes approximately to complete one revolution around earth. |
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| 944. |
Explain the nature of force between two adjacent turns of a solenoid. How does this force affect its length ? |
| Answer» Solution :Use the CLOCK RULE to detemine the magnetic poles when ELECTRIC current passes through a circular coil. Will the adjacent FACES of two coils are acts as similar poles ? | |
| 945. |
The length of a simple pendulum is made one-fourth. Its time period becomes : |
| Answer» Solution :half | |
| 946. |
Why in hand driven grinding machine, handle is put near the circumference of the stone or wheel? |
| Answer» SOLUTION :The HANDLE provided to applythe EFFORT and to increase mechanicaladvantage. | |
| 947. |
Explain why is it difficult for a fireman to hold a hose which ejects large amounts of water at a high velocity . |
| Answer» SOLUTION :When a fireman holds a hose , which i.e ejecting large amounts of WATER at a high velocity then a reaction FORCE is exerted onhim by the ejecting water in the backward direction. This is because of Newton.s THIRD law of motion. As a RESULT of the backward force, the stability of the fireman decreases. Hence it is difficult for him to remain stable while holding the hose. | |
| 949. |
Calculate the molality of a solution prepared by dissolving 10.5g of NaCl is 250 g of H_(2)O. |
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Answer» Solution :MOLALITY`(m)=(N(mol))/(w(kg))=((10.5g//58.44" g "mol^(-1)))/((250g//1000g" "kg^(-1)))=0.719" mol "kg^(-1)` We report this molality as 0.719 m NACL solution. |
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| 950. |
Is work a scalar or a vector quantity? |
| Answer» Solution :Work is a scalar QUANTITY because it has only MAGNITUDE and no DIRECTION. | |