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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.
| 1. |
A uniform cylindrical body when placed in liquid a floats with one third of its length outside the liquid. When placed in liquid B, it floats with one third of its length immersed in the liquid. When the body is made to float vertically in a homogeneous mixture of equal volumes of the two liquids, 25 cm of its length is seen in air. Find the length of the body. |
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Answer» Solution :Let 'l' be the length of the cylindrical body. When the body floats in liquid A, `(1//3)` RD of its length is above the liquid. `:.` the fraction inside the liquid `=2//3` `:.(p)/(p_(A))=(2)/(3)rArrp_(A)=(3)/(2)p` where p and `p_(A)` are densities of the body and the liquid 'A', respectively. Similarly when the body is made to float in liquid B, one-third of it is inside the liquid. `:.(p)/(p_(B))=(1)/(3)rArrp_(B)=3p` where `p_(B)` is the density of the liquid 'B'. When equal volumes of the LIQUIDS are COMBINED to from a HOMOGENEOUS mixture, the density of the mixture `rArrp_(m)=(p_(A)+p_(B))/(2)=(1)/(2)(P_(A)+p_(B))` `=(1)/(2)((3)/(2)p+3p)=(9)/(4)p` `:.(p_(m))/(p)=(9)/(4)or(p)/(p_(m))=(4)/(9):.` Fraction of the body inside the mixture `=(4)/(9)` Fraction of the body outside the mixture `=1-(4)/(9)=(5)/(9)` Given length outside the mixture = 25 cm `:.(5l)/(9)=25cmrArr=45cm` `:.` the total length of the cylindrical body = 45 cm |
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| 2. |
The place of human being in food chainin an ecosystem is as a: |
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Answer» producer |
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| 3. |
The velocities of sound waves in four media P,Q,R and S are 18,000 km//h, 900 km//h, 0km//h, and 1200 km/h respectively. Which medium could be a liquid substance? |
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Answer» P |
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| 4. |
Calculate the wavelength of a sound wave whose frequency is 220Hz and speed is 440 m/s in a given medium. |
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Answer» Speed of the sound wave, `v=440ms^(-1)` Fora sound wave, Speed = Wave length `XX` Frequency `=` THEREFORE `= upsilon//v=440//220=2M` Hence, the wave length of the sound wave is 2m. |
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| 5. |
A metallic sphere is made of an alloy of metels 'P' and 'Q' having specific gravities (or relative densities) 20 and 2, respectively. The sphere weighs 120 g_(wt) in air and 90 gwt in water. Find the percentage of the mass of metal 'P' in the alloy. |
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Answer» Solution :(i) ARCHIMEDE's principle. (ii) R.D `=(W_(1))/(W_(1)-W_(2))` (iii) Volume of the METALLIC sphere = volume of metal P+volume of metal Q (iv) Density `=("mass")/("volume")` |
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| 6. |
State whether the following statements are true or false: (a) A falling stone also attracts the earth. (b) The force of gravitation between two objects depends on the nature of medium between them. The value of G on the moon is about one-sixth((1)/(6)) of the value of G on the earth. (d) The acceleration due to gravity acting on a freely falling body is directly proportional to the mass or the body.The weight of an object on the earth is about one-sixth of its weight on the moon. |
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| 7. |
A body of density rho is immersed in a liquid of density rho_(L).State condition when the body will (i) float (ii) sink in liquid. |
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| 8. |
The speed-time graphs for three objects X, Y and Z are represented on the same graph paper. Which object would cover the highest distance in given interval of time (t)? |
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Answer» Z |
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| 9. |
For a given glass prism, as the angle of incidence increases, theangle of emergence __________ . |
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Answer» decreases `(SIN i_(1))/(sin r_(1)) = (sin i_(2))/(sin r_(2)) = mu`(1) Where `i_(1) and r_(1)` are angle of incidence and refraction at the firstrefracting surface, `i_(2) and r_(2)` are angle of incidence andrefraction at SECOND refracting surface from (1) we can write `(sin i_(1))/(sin r_(1)) = mu` As `mu` of the material of the prism remains constant with increase in angle of incidence `i_(1)` angle of refraction `r_(1)` ALSO increases. Now, `A = r_(1) + r_(2)` But for a given prism, A remains constant `:. r_(1) + r_(2)` = constant. In theabove equation, if `r_(1)` increases due to increase in `i_(1) ` then `r_(2)`must decrease. With decrease in `r_(2)`, angle of EMERGENCE decreases, as ` mu = (sin i_(2))/(sin r_(2))` |
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| 10. |
Calculate the potential difference across the ends of a wire of resistance 2 Omega' when a current of 1.5 A passes through it. |
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Answer» Solution :GIVEN: `R = 20, 7 = 1.5 A` From Ohm.s LAW, `V = IR` POTENTIAL differences `V = 1.5 xx 2=3.0 V` |
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| 11. |
What do you know about Michael Faraday? |
| Answer» Solution :Michael Faraday discovered that a current carrying conductor ALSO gets deflected when it is placed in a magnetif field. Michael Faraday was a British Scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the PRINCIPLES underlying electromagnetic induction, diamagnetism and electrolysis. Although Farady received little FORMAL education he was one of the most influential scientist in history. Faraday was an EXCELLENT experimentalist who conveyed his ideas in clear and simple language. The SI unit of CAPACITANCE is named in his honour, the farad. Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Faraday is one of the greatest scientific discoverers of all time. | |
| 12. |
Mass of a body is 50 kg. What is its weight on earth (g=10 m//s^2) |
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Answer» =` 50xx10` =500 N |
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| 13. |
Two like magnetic poles : |
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Answer» REPEL each other |
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| 15. |
A car moving on a straight path covers a distance of 1 km due east in 100 s. What is (i) the speed and (ii) the velocity, of car? |
| Answer» SOLUTION :(i) 10 m `s^(-1)`, (II) 10 m `s^(-1)` due EAST. | |
| 16. |
A man uses a rough inclined plane of length 3 m to raise a load of 100 kgwt. Ifhe does 2400 J of work and the inclined plane offers 300 N resistance,find the mechanical advantage (Take g=10 m s^(-2)). |
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Answer» Solution :Work done to raise the load = Work done against gravity + work done agianst friction, w = MG ` Sin theta xx 1 + f xx 1` SubstitutingW = 2400 J, mg = 1000 N, 1=3 m, f = 300 N, we get 2400 J = `(1000xx sin theta + 300)xx3` `100 sin theta + 300 = 800` `1000 sin theta = 500` ` sin theta = (500)/(1000)` `sin theta = (1)/(2)` M.A. ` = ("load")/("effort")=(mg)/( mg sin theta + f_(s))` substitute mg` = 1000 N sin theta = (1)/(2)`. `f_(s)=300 N` `MA = (1000)/(1000xx(1)/(2)+300)=(1000)/(800)=(5)/(4)= 1.25` Alternative method : Lengthof the given inclined PLANE 1 = 3 m (given) Work done by the effort, `W_(E)=2400 J ` (given) Let 'E' be the effort. `:. W_(e)=El rArr 2400 = E (3) rArr E = 800 N` Mass of the load = 100 kgwt `:.` Load L = (100) (10) `[:' g = 10 m s^(-2)]` `= 1000 N` `:.` Mechanical advantage (M.A.) ` = (L)/(E)=(1000)/(800)=1.25` |
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| 17. |
What type of scans are used these days to monitor the growth of developing baby in the uterus of the mother? |
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| 19. |
What if the same vehicle is pushed from outside. Will the vehicle moves? |
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| 20. |
An object is allowed to fall freely from the top of a 150 m high tower. At the same time another object is allowed to fall freely from the top of a 100 m high tower. If the acceleration of both the free falling objects is same, then find the difference between their heights after 2 s from their motion. How does the difference of their heights change with the time? |
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Answer» SOLUTION :Difference between their INITIAL HEIGHT `= 50 m,` Difference between their height after 2 s from their MOTION. The difference between heights does not CHANGE. |
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| 21. |
An electric heater is rated 1500 w. How much energy does it use in 10 hours. |
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Answer» Solution :Energy consumed by an ELECTRIC heater can be OBTAINED with the HELP of the EXPRESSION. P = W/T, where, power rating of the heater P = 1500w = 1.5kw Time for which the heater has operated. T = 10H Work done = Energy consumed by the heater Therefore, energy consumed = power `xx` time = `1.5 xx 10 = 15` kwh Hence, the energy consumed by the heater in 10h is 15 kwh. |
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| 22. |
A body weighs 20 gf in air and 18.0 gf in water. Calculate relative density of the material of body. |
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| 23. |
5 electric bulbs of 100 W are used for 8 hours, then …………… unit of energy would be consumed in 1 day. (4,5,8) |
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| 24. |
Avinash is moving with the velocity 8ms^(-1) against the frictional force 10 N acting on him and Kapil is moving with the velocity 3ms^(-1) against the frictional force 25 N acting on him. Whos power would be more? |
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| 26. |
Select the renewable and non renewablesources o energy from the following: a. Coal b. Wood c. Water d. Diesel e. Wind f. Oil |
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| 27. |
Ramesh and Sandeep are two very close friends who study in classes IX and X respectively. One day Ramesh and Sandeep had to go to a neighbouring twon on their bicycles for some work. They had to cross a railway line on the way to the neighbouring town. when Ramesh and Sandeep were going in the afternoon, the railway crossing barrier was open, so they did not have to wait for going across it. Their work in the neighbouring town kept Ramesh and Sandeep bust till late in the evening. On their way back home, when Ramesh and Sandeep reached the same railway crossing, it was quite dark in the night and the railway crossing barrier was down (or closed) indicating that some train was expected to pass through soon. Ramesh was in a hurry to go back home. Ramesh told Sandeep that since he could not hear the sound of approaching train, so they did not know when the train would pass through the crosing and barrier would open. He suggested that instead of keeping on waiting, they should cross the railway tracks by going below the closed barrier by tilting their bicycles and lowering their heads. Sandeep did not agree with Ramesh. Sandeep said that they would not cross the railway tracks as long as the barrier was closed. Suddenly, Ramesh slipped through the barrier and put his ear on the railway track. Sandeep pulled him away from the railway track quickly. As soon as Ramesh was pulled away from the railway track, a super-fast train passed through the same track in the darkness of night without blowing any horn. Sandeep was very angry with Ramesh and scolded him for the risk he had taken. After the train passed through the crossing, the barrier was opened by railway staff. Ramesh and Sandeep then crossed the railway track alongwith their bicycles and reached home safely. (a) How many times more is the speed of sound in railway track then the speed of sound in air? (b) Why did Sandeep not allow Ramesh to cross the closed barrier of railway crossing? (c) Why did Ramesh put his ear to the railway track? (d) Why did Sandeep pull Ramesh away from the railway track? (e) Whatvalues are displayed by Sandeep in this episode? |
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Answer» Solution :(a) Railway track is made of steel. The speed of sound in railway track (made of steel) is about 15 times more than the speed of sound in air. (b) Sandeep did not allow Ramesh to pass through the closed barrier of railway crossing because it is very risky to do so. A closed barrier indicates that a train could pass through his crossing any TIME. And if a person is crossing the railway tracks at the time when a train is approaching very FAST, it can lead to a train accident in which the person can GET injured seriously or even killed (more especially in the darkness of neight). (c) Ramesh put his ear to the railway track to hear the sound of coming train through the railway track made of steel and get an idea of the distance of the incoming train (because the speed of sound in railway track made of steel is very high as compared to the speed of sound in air). (d) Sandeep pulled Ramesh away from the railway track quickly because he did not want Ramesh to be involved in a train accident. (e) The various values displayed by Sandeep in this episode are (i) Awareness that most of the train accidents are fatal (which cause death) (i) Desire to prevent train accident (by not PASSING through)closed railway crossing barrier), and (III) Concern for the safety of his friend (in pulling him away from railway track). 
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| 28. |
Assertion (A) : The distance between two celestial bodies is measured by the unit of light year. Reason (R) : The distance travelled by the light in one year in vacuum is called one light year. |
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| 29. |
The radiations from uranium discovered by Becquerel are________. |
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| 30. |
When a body like earth is moving in a circular path the work done in that case is zero because: |
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Answer» CENTRIPETAL FORCE acts in the DIRECTION of motion of the BODY |
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| 31. |
Ravi is a student of class IX in a Delhi school. This year all the students of class IX were going to visit Kashmir during the winter holidays alongwith some of their teachers. All the students were asked to pack heavy woolen clothes with them because winter in Kashmir is very severe. Ravi had recently studied a particular chapter in science. Keeping that in mind, Ravi also purchased a pair of special type of shoes from the market and packet it alongwith his luggage. When the students reached Srinagar, it was extremely cold. When the students got up in the morning next day, they were told that heavy snowfall is going on in this area since last night and that there were thick layers of snow all around their hotel. Most of the students had not seen snowfall before. So, all the students and teachers decided to walk and play on fresh falling snow. Ravi put on his special ordinary shoes while walking on snow. It was noticed that the feet of all other students and teachers wearing ordinary shoes were sinking into soft snow making it very difficult for them to walk on soft snow. But this was not so with Ravi. Ravi could walk easily even on soft snow (without his feet sinking into it). All the students were very jealous of Ravi. But the teachers were all praise for Ravi. (a) Which concept of science is involved in the incident which took place on soft snow? (b) Why do the feet of a student wearing ordinary shoes sink into soft snow? (c) What are the special shoes worn by Ravi called? How do they differ from ordinary shoes? (d) Explain why, by wearing special shoes, Ravi could walk easily on soft snow (without his feet sinking into soft snow). (e) What are a pair of long, narrow pieces of hard flexible material fastened under the feet for sliding very fast on the slopes of snow covered mountains called (which work on the same principle as snow shoes)? (f) What values are displayed by Ravi in this episode? |
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Answer» Solution :(a) Pressure. (b) The feet of a student wearing ordinary shoes sink into SOFT snow because due to the small size of the sole of the shoes, the weight of a student falls on a small area of soft snow producing a large pressure. (c) The special shoes worn by Ravi are called 'snow shoes'. The area of sole of snow shoes (which comes in contact with snow) is MUCH bigger than the area of sole of ordinary shoes worn by us in everyday life. (d) By wearing snow shoes Ravi could walk easily on soft snow (without SINKING into it) because due to large area of the sole of snow shoes, the weight of Ravi is spread over a large area of soft snow producing small pressure. (e) Skis (SINGULAR: Ski). (f) The values displayed by Ravi in this episode are (i) Knowledge of the CONCEPT of pressure (ii) Application of knowledge in real-life situations, and (iii) Foresight (in taking along snow shoes expecting snowfall in Kashmir during winter). |
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| 32. |
A jeweller claims that he makes ornaments of puregold that has a relative density of 19.3. He sells a bangle weighing 25.25 gf to a person. The clever customer weighs the bangle when immersed in water and finds that it weighs 23.075 gf in water. With the help of suitable calculations, find outwhether the ornament is made of pure gold or not. |
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| 33. |
State two properties of the medium on which the speed of sound in it depends. |
| Answer» SOLUTION :(i) ELASTICITY (II) DENSITY. | |
| 34. |
A shpere of iron and another of wood, both of same radius are placed on the surface of water. State which of the two will sink? Give reason to your answer. |
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| 35. |
A boy is running on a circular path of radius r at the constant speed 20 ms^(-1), then he is said to perform motion .......... (with constant velocity, with acceleration, with constant acceleration) |
| Answer» SOLUTION :with CONSTANT ACCELERATION | |
| 36. |
The time of arrival and departure of a train at three stations A, B and Cand the distance of stations B and C from A are given in the following table: Plot and interpret the distance-time graph for the train assuming that its motion between any two siations in uniform. |
Answer» SOLUTION :
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| 37. |
Suppose the hydrometer is dipped in a liquid of density greater than that of water. Will the liquid surface be above or below the marking of 1? |
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| 38. |
A free falling ball is an example of motion. (constant velocity, constant acceleration, uniform) |
| Answer» SOLUTION :CONSTANT ACCELERATION | |
| 39. |
A simplependulum is completely submergedunder water . Discuss the variation in its timeperiod. |
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Answer» Solution :(i) Massmeasuredis ACCURATE if THEBEAM is HORIZONTAL. (ii) IFTHE beamis nothorizontaldoesit AFFECT theturningpointsobserved? |
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| 40. |
Assertion : For observing the traffic at a hairpin bend in mountain paths a plane mirror is preferred over convex mirror and concave mirror. Reason : A convex. mirror has a much larger field of view than a plane mirror or a concave mirror. |
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Answer» If both ASSERTION and REASON are TRUE and reason is the CORRECT explanation. |
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| 41. |
(a) Define work done by a constant force. Write its SI unit and define this unit. (b) A 3000kg truck at a speed of 72kmh^(-1) stops after covering some distance. The force applied by brakes is 2400 N. Compute the distance covered and work done by this force. |
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Answer» Solution :(a) The work done by a constant force acting on a body is the product of the force and the distance moved by its point of application in the direction of the force. The SI unit of work is the joule. Definition of the joule : The amount of work done on a body when a force of 1 N displaces it by 1 m along the line of action of the force. (b) Here, `m=3000kg,` `u=72kmh^(-1)=72xx(5)/(18)ms^(-1)=20ms^(-1)`, F (applied by the brakes) = 2400 N, `s=?`, `W=?` The force exerted by the brakers, `F=ma` `therefore a=(F)/(m)=(2400)/(3000)=0.8ms^(-2)` Here, the force is braking force, so, the value of a is `-0.8ms^(-2)`. Now, `V^(2)-u^(2)=2AS` `therefore (0)^(2)-(20)^(2)=2xx(-0.8)xxs` (`v=0`, because the TRUCK stops) `therefore -(400)=2xx(-0.8)xxs` `therefore s=(400)/(2xx0.8)=250m` So, the truck will stop after covering a distance of 250 m. Work done by the brakes, `W=Fs=2400Nxx250m=6xx10^(5)J` Work done by the force applied by the brakes is `6xx10^(5)J`. |
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| 42. |
A car is moving on a striaght road with uniform acceleration. The following table gives the speed of the car at various instants of time : {:(,"Speed"(m//s)" ":,,5,,10,,15,,20,,25,,30),(,"Time"(s)"":,,0,,10,,20,,30,,40,,50):} Draw the speed-time graph by choosing a convenient scale. Determine from it : (i) the acceleration of the car. (ii) the distance travelled by the car in 50 seconds. |
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Answer» Solution :We take a graph PAPER and plot the above given TIME values on the x-axis. The corresponding speed values are plotted on the y-axis. The speed-time graph obtained from the given readings is shown inFigure 42. Please not that in this case, when the time is 0, then the speed is not 0. The body has an initial speed of 5m/s which is represented by point A in Figure 42. We will now answer the questions asked in this sample problem. (i) Calculation of Acceleration. We know that : Acceleration = Slope of speed-time graph `""` = Slope of line AF(see Figure 42) `""=(FG)/(AG)` Now, if we look at the graph shown in Figure 42, we will find that the value of speed at point F is 30 m/s and that at point G is 5 m/s. Therefore, `""` FG= 30-5 = 25 m/s Again, at point G, thevalue of time is 50 seconds whereas that at point A is 0 second. Thus, `""` AG= 50-0 `""` = 50 s Now, putting these values of FG and AG in the above relation, we get : `" "` Acceleration = `(25 m//s)/(50s)` `""= 0.5 m//s^(2)` (II) Calculation of Distance Travelled. The distance travelled by the car in 50 seconds is equal to the area under the speed-time curve AF. That is, the distance travelled is equal to the area of the figure OAFH (see Figure 42). But the figure OAFH is a trapezium. So, Distance travelled = Area of trapezium OAFH `""=(("Sum of two parallel sides")xx"Height")/(2)` In Figure 42, the two parallel sides are OA and HF whereas the heights is OH. Therefore, Distance travelled = `((OA+HF)xxOH)/(2)` `""=((5+30)xx50)/(2)` `""=(35xx50)/(2)` LTBRGT `""`= 875 m |
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| 43. |
Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher. |
| Answer» SOLUTION :YES, for a uniformly moving OBJECT suppose an object is moving with constant VELOCITY. The net force acting on it is zero. But there is a displacement along the motion of the object. Hence, there can be a displacement without a force. | |
| 44. |
Speed of a body in motion is doubled. Its kinetic energy is now …………. Times the original kinetic energy. |
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Answer» two Now, doubling its speed, `E_(k).=(1)/(2)m(2v)^(2)` `=(1)/(2)mv^(2)xx4=4E_(k)` Thus, the kinetic energy of the OBJECT becomes four TIMES. |
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| 45. |
The repeated reflection that results in persistence of sound is called ………………….. . |
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| 46. |
State the numerical value of the frequency of oscillation of a seconds' pendulum. Does it depend on the amplitude of oscillation ? |
| Answer» SOLUTION :`0.5 s^(-1)` , NO | |
| 48. |
A car anda bus are travelling with the same velocity. Which has greater momentum ? Why? |
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| 49. |
P,Q and r are three capillary tubes. If these are dipped in water. Which has greater capillary rise? . |
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| 50. |
The magnitude of zero error of the spring balance and least count of the measuring cylinder |
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Answer» 2.5g and 0.1m |
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