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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.
| 251. |
The potential energy of a frequency falling object decreases progressively. Does this violate the law of conservation of energy? Why. |
| Answer» Solution :No the process does not violate the law of conservation of energy. This is because when the body falls from a HEIGHT, then its potential energy changes into KINETIC energy PROGRESSIVELY. A decrease in the potential energy is equal to an increase in the kinetic energy of the body. During the process, TOTAL mechanical energy of the body remains conserved. Therefore the law of conservation of energy is not VIOLATED. | |
| 253. |
An iron sphere of mass 10 kg has the same diameter an an aluminium sphere of mass 3.5 kg both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same : |
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Answer» ACCELERATION |
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| 254. |
Four balls,A,B,C,D displace 10 mL ,24 mL,15 mL, and 12 mL of a liquid respectively ,when immersed completely.The ball which will undergo the maximum apparent loss in weight will be : |
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Answer» A |
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| 255. |
The strength of a magnetic field increases as _________ |
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Answer» the NUMBER of magnetic LINES of force passing through a given AREA increases |
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| 256. |
What kind of energy conversions sustain the water cycle? |
| Answer» SOLUTION :Solar energy causes EVAPORATION of the water in oceans. Rivers, lakes, ponds and trees. The water vapour forms clouds. The condensation of water vapour causes rainfall. The water stored in dams POSSESS potential energy. The FLOWING water in rivers posses kinetic energy. This can be changed into electrical energy at hydroelectric plant. | |
| 258. |
Acceleration of a car in motion is 1.5 m s^(-2). How much is the increase in velocity in 4s? |
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Answer» `6 ms^(-1)` `therefore` Change in velocity (increase) = Acceleration `xx` Time interval `= (1.5 ms ^(-2)) xx (4S)` `=6 ms ^(-1)` |
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| 259. |
Hetasvi, having her own mass 50 kg, climbs 20 m height along with 30 kg mass in 40 s. Calculate her power and work done. (Take g=10ms^(-2)). |
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| 260. |
A body floats in a liquid with a part of it submerged inside liquid. Is the weight of floating body greater than, equal to or less than upthrust? |
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| 261. |
What is resistance? |
| Answer» Solution :The resistance ( R ) is the MEASURE of OPPOSITION offered by the component to the FLOW of electric CURRENT through it. | |
| 262. |
Choose the correct answer . 1. The size of an air bubble rising up in water ………………. |
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Answer» decreases |
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| 263. |
A truck from rest and rolls downa hill with a constant acceleration. It travels a distance of 400 m in 20 s. Find its acceleration . Find the force acting on it its mass is 7 metric tonnes (Hint : 1 metric tonne = 1000 kg) |
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Answer» SOLUTION :INITIAL velocity ,u=0 DISTANCE travelled , S=400 m, time taken t=20S We know, `S=ut+1//2at^2` or `400 =0+1//2a(20)^2` `A=2ms^(-2)` Now, `m=7MT=7000kg, a=2ms^(-2)` or F=ma `=7000xx2 =14000 N` |
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| 264. |
A charge of 2xx10^(4)C flows through an electric heater. The amount of electrical energy converted into thermal energy is 5 MJ. Compute the potential difference across the ends of the heater. |
| Answer» Solution :`V= W"/"q" that is " 5xx10^(6)J"/"2xx10^(4)C= 250V` | |
| 265. |
If a tennis ball (mass 58.5g) and a cricket ball (mass 163 g) are the reach a certain distance when hit with a cricket bat, Which is to be hit with greater force ? The tennis ball / the cricket ball |
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| 266. |
A key of a mechanical piano is struck gently and then struck again but much harder this time. In the second case : |
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Answer» SECOND will be lounder but PITCH will not be different |
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| 267. |
According to wave theory, different colours of light is due to |
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Answer» SOLUTION :What is light? How light is emitted in a discharge tube ? How is the frequency of light related to the ENERGY of the PHOTONS ? ? How is the frequency of light related to the colour? |
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| 268. |
Kalpesh, before going out, takes the reading of the odometer of his motorcycle. It was 8245 km. Driving at uniform velocity of 60 km h^(-1)for 30 min on a straight highway, he reaches his friend's village. What would be the odometer reading of his motorcycle there? |
| Answer» SOLUTION :READING of ODOMETER = 8275 KM | |
| 269. |
An object is thrown in vertical upward direction with velocity 'u' then the maximum height attained by the object would be.... |
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Answer» `(u)/(G)` At maximum height, the final VELOCITY of the object v=0 and for motion in upward direction `a =-g ` `therefore 2 (-g) H _(max) = 0 -u^(2) (because s = h _(max))` `therefore h _(max) = (u ^(2))/(2g)` |
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| 270. |
What is mean by free fall? |
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| 271. |
Speed of sound depends on |
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Answer» TEMPERATURE of medium |
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| 272. |
A mass of 10 kg is at a point A an a table. It is moved to a point V. If the line joinning A and B is horizontal. What is the work done on the object by the gravitational force? Explain your answer. |
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Answer» SOLUTION :WORK DONE by gravity DEPENDS only on the vertical displacement of the body. It does not depend upto the path of the body. Therefore, work done by gravity is given by the expression. w = mgh Where vertical displacement, h = 0 Therefore w = MG `xx` 0 = 0 Hence, the work done by gravity on the body is zero. |
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| 273. |
Find out the reasons An athlete doing a long jump starts his run from a distance. |
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| 274. |
When starter motor of a car is switched on for 0.8 s, a charge 24 C passes through the coil of the motor. Calculate the current in the coil. |
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| 275. |
Transformer works on |
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Answer» AC only |
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| 276. |
An echo returned in 3 s whatis the distance of the reflecting surface from the source, given that the speed of the sound is 342m/s |
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Answer» Echo RETURNS in time, `t=3s` Distance travelled by sound `=vxxt=342xx3=1026m`. In the given time travel sound has to travel a distance that is twice the distance of the reflecting surface and the source. Hence the distance of the reflectingsurface from the source `=1026//2m=513m` |
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| 277. |
A body weighs 450 gf in air and 310 gf when completely immersed in water. Find: (i) the volume of the body (ii) the loss in weight of the body, and (iii) the upthrust on the body. State the assumption made in part (i) |
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Answer» Assumption : DENSITY of water `=1.0gcm^(-3)` |
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| 278. |
Electroplating is an example for….. |
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Answer» HEATING effect |
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| 279. |
The length of an object was measured to be 30 cm by a linear scale of least count 0.1 cm. what is the % error? |
| Answer» SOLUTION :% ERROR`=("LEAST count")/("MEASURED value")XX100=(0.1)/(30)xx100=0.33%` | |
| 280. |
A train is travelling at a peed of 90 km h ^(-1). Breakes are applied so as to produce a uniform acceleration of - 0.5 ms ^(-2). Find how far the train will go before it is brought to rest. |
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Answer» Solution :Here, `U = 90 km h ^(-1) =(90 xx 1000)/(3600) = 25 ms ^(-1) ,` `a =- 0.5 ms ^(-2),` `v =0` (Because TH train is brought to REST.) `v ^(2) -u ^(2) = 2 as` `therefore 0- (25) ^(2) =2 xx (-0.5) xx s` `therefore s = (- (25 xx 25))/(- 2 xx 0.5) = 625 m` The tranin will cover a DISTANCE of 625 m before it comes to rest. |
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| 281. |
Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why? |
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Answer» SOLUTION :Yes, the acceleration in an OBJECT COULD be zero, when the resulant of all the FORCES ACTING on the object is zero. `a=(F)/(m)=(0)/(m)=0` |
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| 282. |
The distance-time graph of three objects A, B and C is shown below. Study the graph and answer the following questions : : Distance-time graph) (a) Which of the three is travelling the fastest? (b) Are all three ever at the same point on the road ? (c) How far has travelled when B passes A? (d) How far has B travelled by the time it passes C? |
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Answer» Solution :(a) speed = slope of distance-time GRAPH `= tan theta` Here, from graph `theta _(1) gt theta_(2) gt theta _(3),i.e.,` speed of `B gt` speed of `C gt ` speed of A. `THEREFORE B` is travelling the fastest. (b) No, the three lines do not meet at the same point. (c ) When B passes A,C is at a distance of 8 KM (approx.) from the origin. (d) By the time B passes C, B has travelled `5.7 km `(approx). |
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| 283. |
0cdot1 kg of a substance is taken as sample and combusted on sample holder of a bomb calorimeter. The temperature of 1 kg of ice present in external chamber has risen from 0^(@)C" to "50^(@)C. What is the calorific value of the given sample? (Given that specific heat capacity of water = 42 J kg^(-1)K^(-1)) Specific latent heat of fusion of ice =336000 J kg^(-1) |
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Answer» Solution :Kinetic enrgy at the bottom = Potential ENERGY (mgh) at the given height. Heat gained `=(80)/(100)xxmgh=ms Delta theta` `rArr""Delta theta =(80)/(100)xx(gh)/(s)` `"Given ",g=1000 CM s^(-2) = 10 ms^(-2)` `h= 6 m and s=2 JKG^(-1) K^(-1).` `rArr""Deltatheta=(80)/(100)xx(10xx6)/(2)=24^(@)C or 24 K.` |
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| 284. |
What if the mass of both the bodies are doubled? |
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| 286. |
Define : Average speed |
| Answer» SOLUTION :The total DISTANCE travelled by an object DIVIDED by the total TIME taken is called the average SPEED of the object. | |
| 287. |
It is more difficult to roll a filled tar drum than a empty drum Which of two has a greater mass ? |
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| 288. |
What is the audible range of the average human ear ? |
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| 289. |
(a) What is kinetic energy due to ? Derive an expression for it in case of a body of mass m moving with velocity v. (b) If W is the work done to give a speed v to a car from rest, how much work is done to increase its speed to 2 v ? |
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Answer» Solution :(a) N/A (b) `W = (1)/(2) mv^2`, `W' = (1)/(2) m (2 V)^2 - (1)/(2) mv^2 = (3)/(2) mv^2 = 3 ((1)/(2) mv^(2)) = 3 W`. |
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| 290. |
Fig. 9.26 below shows two conductors A and B. Their charges and potentials are given in the diagram. State the direction of (i) flow of electrons, and (ii) flow of current, when both the conductors are joined by a metal wire. |
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| 291. |
City an experiment to show that sound needs a material medium for its propagation. |
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Answer» SUSPEND the bell inside the jar, and press theswitch of the bell. You will be able to hear the bell ring. Now pump out the air from the glass jar. The SOUND of the bell will become FAINTER and after some time the sound will not be heard. This is so because almost all air has been PUMPED out. This shows that sound needs a material medium to travel. 
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| 292. |
How will you measure the least count of Varnier Caliper ? |
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Answer» Solution :Least COUNTOF Vermier Caliper is the ratio of one smallest main scale division to total number of Vermier scale division i.e.,L.C. = 0 . 1 m m = 0 . 0 1 (or) L.C. = 1 MD - IVSD = 1 . 0 m m - 0 . 9 m m = 0 . 1 m= 0 . 01 cm |
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| 293. |
Gravitational force on the surface of the moon is only 1/6 as strong as gravitational force of the earth. What is the weight in newtons of a 10kg object on the moon and on the earth. |
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Answer» SOLUTION :WEIGHT of an object on the moon =1/6x weight of an object on the earth. Also weight=Mass `XX` Acceleration. Accelecration due to GRAVITY, `g=9.8m//s^(2)`. Therefore, weight of a 10 KG object on the earth `=10xx9.8=98N` And, weight of the same object on the moon `=1.6xx9.8=16.3N`. |
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| 295. |
Assertion (A) : To float, body must displace liquid whose weight is equal to the actual weight. Reason (R) The body will experience no net downward force in that case. |
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Answer» If both assertion and REASON are true and reason is the correct EXPLANATION of assertion. |
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| 296. |
A car is moving with the initial velocity 15 m/s.Car stopped after 5s by application of breaks. Find the retardation (Decelaration). |
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Answer» Solution :t = 5 s V =0 m/s U = 15 m/s u = 15 m/s a = ? SUBSTITUTING the values in the following equation. v = u + at 0 = 15 + `(a xx 5)` a = `(-15)/(5)` a = - 3 `m//s^(2)` |
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| 297. |
Two wires of equal length a diameter, one mad of copper and the other of nichrome, are connected in series and the currnet through them is slowly increased . Which of thetwo wires heats up faster ? Explain . Alsoexplain what happen if the two are connected in parallel. |
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Answer» SOLUTION :Heat energy produced in a wire when electri current passes through it increases with resistance. Which AMONG the two wires has HIGHER resistance ? what happens to the effective resistance when two wires are connected in parallel ? How will it AFFECT the heat produced in the wire if the effective is less than the individual resistance ? |
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| 298. |
The Earth exerts more force on heavier bodies than on lighter bodies, Why is it then that when dropped, heavier bodies don’t fall faster than lighter bodies? |
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Answer» Solution :(i) Consider Newton's laws of MOTION and EQUATIONS of motion. (ii) When the bodies are DROPPED from the same height, with zero initial velocity, will the value of the acceleration due to gravity actiong on the bodies REMAIN CONSTANT (same)? Will distance moved by the bodies under gravity depend on its weight? Is factor of 'mass' involved in the equations of motions? |
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| 299. |
Examine the graph and answer the following question. Is the motion of the object is uniform/non uniform |
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| 300. |
Themaximum force than can be borne by the nut placed in a cracker (shown in the figure) is 200 N. The length of the cracker is 20 cm and thenut is placed at a distance of 15 cm from the free end of the cracker. If a boy canapply a maximum force of 25 N, find whether he can crack the nut. If not, find the length of the extension rod that should be attached to the cracker handleso that the boy can crack the nut. |
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Answer» Solution : (i) Nut cracker isa second-order LEVER. (ii) Find the load from the given INFORMATION. (iii) Find thelengths of the effort arm and the load arm from the given information. (IV) Relate mechanicaladvantage, load and effort. (v) Find the required effort andcompare it with the force that can be EXERTED by the BOY. (vi) Consider the force that can beexerted by theboy as effort and find the length of the effort arm. (vii) Compare the length of the effort arm obtained and its given length. (viii) Boy cannot crack the nut Extension = 20 cm |
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