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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.
| 1601. |
An aluminium ballis fully immersed in distilled water, well water, sea water and inland lake water, one by one. The aluminium ball will appear to suffer the maximum loss in weight when immersed in: |
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Answer» DISTILLED water |
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| 1602. |
A constant force acts on an object of mass 5 kg for a duration of 2 s. It increases the object's velocity from 3 m s^(-1) to 7 m s^(-1). Find the magnitude of the applied force. Now, if the force was applied for a duration of 5 s, what would be the final velocity of the object ? |
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Answer» Solution :We have been GIVEN that u = 3 `ms^(-1)` and v = 7 `ms^(-1), t = 2` s and m = 5 kg. From Eq. we have, `F = (m(v-u))/(t)` Substitution of values in this relation gives `F = (5kg(7ms^(-1) - 3MS^(-1))/(2s) = 10N` Now, if this force is APPLIED for a duration of 5 s (t = 5 s), then the final velocity can be CALCULATED by rewriting Eq. as `v = u + (Ft)/(m)` On substituting the values of u, F, m and t, we get the final veloctiy, `v = 13ms^(-1)` |
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| 1603. |
The velocity-time graph of a body in motion is a straight line inclined to the time axis. The correct statement is : |
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Answer» velocity is UNIFORM |
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| 1604. |
The charge supplied to a glass rod at one of its ends stays of the same place. |
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| 1605. |
Fill in the following blanks with suitable words: (a) An echo is simply a.........sound. (b) Pitch of sound depends on............. (c) Loudness of sound depends on........... (d) Quality of sound depends on......... (e) Echoes are caused by the ...............of sound. |
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| 1606. |
What are the differences between cathode rays and canal rays ? |
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| 1607. |
A boy is moving on a straight road against a frictional force of 5 N. After travelling 1.5 km, he forgot the path at cross roads of radius 100m. He moves on the circular path for one and half cycle and then he moves forward up to 2 km. Calculate the work done by him. |
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Answer» Displacement on the circular PATH : 1 cycle= 0 and half cycle = `2r=2xx100` `=200M` Total displacement = `1.5km+200m+2km` `=3700m` Work done by the BOY = `Fxxs` `=5Nxx3700m` `=18500J` |
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| 1608. |
A bicycle initially moving with a velocity 5.0 "m s"^(-1) accelerates for 5 s at a rate of 2 "m s"^(-2) . What will be its final velocity ? |
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| 1609. |
Give two practical applications of reflection of sound waves. |
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Answer» Working of a stethoscope is also based on reflection of sound. In a stethoscope is also based on reflection of sound. In a stethoscope the sound of the patient.sheart beat reaches the doctor.s ear by MULTIPLE reflection of sound. |
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| 1610. |
State which of the following situation are possible and give an example for each of these An object moving in a certain direction with an acceleration in the perpendi cular direction. |
| Answer» Solution :POSSIBLE, when a car is MOVING in a circular track, its ACCELERATION is prependicular to its DIRECTION. | |
| 1611. |
A wound wave propagates in a medium which has the property/properties of |
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Answer» INERTIA |
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| 1612. |
What is the name of the strings which vibrate in our voice box when we talk? |
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| 1613. |
What do you mean by the audible range of frequency? |
| Answer» SOLUTION :The RANGE of frequency within which the sound can be heard by a HUMAN being is CALLED the audible range of frequency. | |
| 1614. |
The stone tied to a thread is suspending from a spring balance. Write down instances where the force of gravity is felt. |
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Answer» • STONE which is THROWN upwards reaches the GROUND. |
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| 1615. |
A man works with the constant power 100 W. How much mass of an object can he lift upward at the uniform velocity 1ms^(-1)? (g=10ms^(-2)) |
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Answer» `therefore m=(P)/(gv)=(100)/(10xx1)=10KG` |
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| 1617. |
Rockets are used to launch artificial satellites. State the law of motion related to the rocket launching |
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| 1618. |
Kerosene and saline water are taken in two beakers. The same stone is immersed in both liquids. In which liquid, more weight difference is experienced? |
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| 1619. |
Kerosene and saline water are taken in two beakers. The same stone is immersed in both liquids. In which liquid, the stone experiences more buoyancy? |
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| 1620. |
Find the mass of an object weighing 98 N. |
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Answer» Solution :Given :The weight of the object = 98 N We know that weight W = MG `:. M = (w)/(G) = (98N)0/(9.8Nkg^(-1))=10 kg` |
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| 1621. |
A bar magnet is suspended vertically from a rigid support at earth's magnetic south pole such that its north pole points downwards, as shown in the figure. What would be the geometrical shape obtained if we join all the null points along a horizontal plane passing through the centre of the magnet. how is the size of this geometric shape related to the pole strength of the magnet. |
| Answer» Solution :The magnetic field get CANCELLED at a particular point between the two wires as their directions are opposite to each other. THEREFORE, only ONE NULL point can be obtained. | |
| 1622. |
A ball is dropped from a height. If it takes 0.2s to cross the last 6m before hitting the ground, find the height from which it is dropped. Take g = 10 m/ /s^(2) (AS_(1)) |
| Answer» SOLUTION :`48.05 m` | |
| 1623. |
The volume of 50g of a substance is 20cm^(3) s. If the density of water is 1gcm^(3), will the substance float or sink. |
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Answer» SOLUTION :If the density of an object is more than the density of liquid, then it sinks in the liquid. On the other hand if the density of an object is less than the density of a liquid, then it FLOATS on the surface of the liquid. Here, density of the SUBSTANCE =Mass of the substance/ volume of the substance `=50//20=2.5gcm^(-3)` The density of the substance is more than the density of water `(1GCM^(-3))`. Hence, the substance will sink in water. |
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| 1624. |
Which of thekepler's laws of planetary motion led Newton to establish the inverse-sguare rule for gravitational force between two bodies |
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| 1625. |
Fill in the blanks :- Burning match stick can possesses ………….. |
| Answer» SOLUTION :KINETIC ENERGY | |
| 1626. |
A body moves from rest with a uniform acceleration and travels 270 m in 3 s. Find the velocity of the body at 10 s after the start. |
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| 1627. |
Distinguishbetween loudnessand intensity of sound. |
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| 1628. |
Assertion (A) : The scientifically correct expression is "The mass of the bag is 10 kg" Reason (R) : In everyday life , we use the term weight instead of mass. |
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| 1629. |
A 10 kgball is dropped from a height of 10m. Find (a) the initial potential energy of the ball. (b) the kinetic energy justbefore it reaches the ground, and (c ) the speed just before it reaches the ground.(AS_(1)) |
| Answer» SOLUTION :980J, 980J, 14m/s | |
| 1630. |
When a piece of chalk is used on a black board, particles of the chalk stick to the board. Why? |
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| 1631. |
(a) What do you understand by the term "transformation of energy" ? Explain with an example. (b) Explain the transformation of energy in the following cases : (i) A ball thrown upwards. (ii) A stone dropped from the roof of a building. |
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| 1632. |
What is velocity os sound? Why does sound travel faster is summer season than in winter. |
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| 1633. |
A book of mss 1 kg is raised through a height .h.. If the potential energy increased by 49 J, find the height raised. |
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Answer» SOLUTION :The increase in potential energy = mgh That is , mgh = 49 J (1) (9.8)h = 49 J The HEIGHT raised, `h = (49) //(1xx9.8)` = 5M |
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| 1634. |
Jagdish is a student of class IX in a city where electricity supply comes from a thermal power house. The state Government has recently raised electricity tariff substantially due to which the electricity bill received by Jagdish's family this month is very high. Jagdish's family was worried about heavy electricity bills to be paid every month from now onwards. Jagdish was worried too. Jagdish thought over the problem and came out with some suggestions. He explained the various steps to be taken to reduce the electricity bill to some extent to his parents. His father and mother liked his ideas. Even his younger sister promised to cooperate in cost-cutting measures. When the suggestions made by Jagdish were put into practice, the next month's electricity bill was substantially lower than expected. Everyone in the family was happy. Because 'money saved' is 'money earned' (a) What is meant by a thermal power house? (b) What fuels are usually used in thermal power houses? (c) How is electricity produced at a thermal power house? (d) What energy transformations take place at a thermal power house? (e) What steps do you think were suggested by Jagdish to reduce the consumption of electricity in his house? (f) What values are displayed by Jagdish in this episode? |
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Answer» Solution :(a) The term 'thermal' means of or related to heat. A thermal power house is an installation where heat energy produced by the combustion of a fuel (or burning of a fuel) is used to generate electricity. (b) The fuels used in thermal power houses are usually coal and natural gas. (c) At a thermal power house, coal (or natural gas) is BURNT to OBTAIN heat energy. This heat then boils water to form steam. The high PRESSURE steam turns the steam turbine. The steam turbine then drives (or rotates) the electric generator (or alternator) to produce electricity. (d) At a thermal power house, when coal (or natural gas) is burnt, then the chemical energy of coal (or natural gas) is transformed into heat energy. This heat energy converts water into steam. The high pressure steam turns the steam turbine and transforms the heat energy into kinetic energy of TURNING turbine. The kinetic energy of turbine then rotates the electric generator. The electric generator transforms kinetic energy into electrical energy. These energy transformations can be written as: Chemical energy `rarr` Heat energy `rarr` Kinetic energy `rarr` Electrical energy (e) The various steps which could have been suggested by Jagdish to reduce the consumption of electricity in his house are: (i) Switch off the lights, fans, TV and other electrical appliances when not required (to prevent wastage of electricity). (ii) Replace all the traditional filament-type electric bulbs by CFLs (Compact Fluorescent Lamps) because CFLs consume much less electricity. (iii) Use solar water heater (instead of electric geyser) to obtain hot water. (iv) Use solar cooker to cook some types of foods, whenever possible. (v) Get the household electric wiring checked properly by an electrician to prevent the leakage of electricity, if any. (f) The various values displayed by Jagdish in this EPISODE are (i) Awareness of various steps to save electricity (ii) Concern for the conservations of fossil fuels (coal and natural gas) which are used to generate electricity, and (iii) Desire to reduce electricity bill of his house. |
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| 1635. |
What is the heat in joules required to raise the temperature of 25 grams of 0^@C to 100^@C? What is the heat in Calories? (Specific heat of water =4.18 J//g^@C ) |
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Answer» SOLUTION :Given m=25 G , `DeltaT`=(100-0)=`100^@C` or in terms of KELVIN (373.15-273.15)=100K, `C=4.18J//g^@C` Heat energy required ,Q=m x C x `DeltaT` =25 x 4.18 x 100 = 10450 J |
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| 1636. |
The recent horrific strom surge flooding New Jersey and New York in US by Hurricane Sandy was almost prefectly predicted well in advance, but was more extrema then the averge person might expect from a minimal hurricane. There is a metric that quantifies the energy person might expect from a minimal hurricane. There is a metric that quantifies the energy of a strom based on how far out tropical storm force winds extends from the centre, known as Integrated Kinetic Energy (IKE). (i) What is Sandy's ranking in terms of IKE among all the hurricanes withnessed so far ? (ii) What is the IKE of Sandy ? (iii) How was sandy different from Hurricance Katrina ? (iv) Which human value did Sandy generate among the people round the globe? |
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Answer» Solution :(i) Sandy's IKE rankssecond among all the hurricanes so far- Hurricane Isabel in 2003 was more DEVASTATING. (ii) Over 140 TJ (1 TJ = 1 trillion joule = 2,77, 778 kWh) - it generated more energy then Hiroshima ATOMIC bomb. (iii) Katrina's IKE was more concentrated whereas Sandy's IKE was more spread out. (iv) Universal sympathy and deep CONCERN for those affected by Sandy's outrage. |
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| 1637. |
An object is placed at a distance of 20 cm from a convex mirror of radius of curvature convex cm. At what distance from theobject should a plane mirror be placed so that the images due tothemirror andthe planemirror are on the same plane? |
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Answer» Solution :FOCAL length =` ("radius of curvature ")/2 = 40/2 = 20` cm Object distance U =- 20CM(from SIGN convention) From mirror formula,  Distance between theobject and the image is 20 + 10 = 30 cm. Since for plane mirrorobject distance is equal to image distance, theplane mirror should be placed at a distance `30/2 = 15` cm from theobject, for theimage of theplane mirror and spherical mirror to be in the same plane. |
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| 1638. |
{:(,"Column I",,"Column II"),(1.,"Unit of work",a.,"Kinetic energy"),(2.,"Unit of power",b.,"potential energy"),(3.,"Energy present in",c.,"newton"),(,"compressed spring",d.,"joule"),(4.,"Energy present in",e.,"joule second"^(-1)),(,"the bullet released",,),(,"from the gun",,):} |
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| 1639. |
Action and reaction forces |
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Answer» Acts on same BODY |
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| 1640. |
Car A of mass 1000 kg moves on a horizontal straight road with speed 36kmh^(-1). If the force resisting the motion is 100 N, then find the power of the engine. Now, after covering 200 m distance, car A collides with a stationary car B of same mass and becomes stationary. As a result car B start moving on the horizontal road, then what would be the speed of car B just after the collision? (The engine of car B is off.) |
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Answer» Frictional FORCE = 100 N POWER of engine of car A, `P=Fv` `=100xx10(because V=10ms^(-1))` `=1000W` USING the law of conservation of momentum, `m_(A)u_(A)+m_(B)u_(B)=m_(A)v_(A)+m_(B)v_(B)` `(1000xx10)+(1000xx0)=(1000xx0)+(1000xxv_(B))` `therefore v_(B)=10ms^(-1)` |
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| 1641. |
How are fuels, such as coal and petroleum formed? |
| Answer» Solution :Millions of years ago the remains of PLANTS and animals got buried under the earth. Due to various actions and high TEMPERATURE and PRESSURE they got converted into fossil FUELS like coal and petroleum. | |
| 1642. |
During an experiment, a signal fromspaceship reached the ground station in five minute. What was the distance of the speceship from the ground station ? The signal travels at the speed of light, that is, 3 xx 10^(8) ms ^(-1). |
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Answer» SOLUTION :Time = 5 minute `= 5 xx 60S = 300s ` SPEED `= ("Distance")/("Time") ` `therefore` distance = speed `xx` time `= 3 xx 10 ^(8) xx 300` `= 900 xx 10 &(8)` `= 9 xx 100 xx 10 ^(8)` `= 9 xx 10 ^(10),` The distance of the spaceship from the ground is `9 xx 10 ^(10) m (or 9 xx 10 ^(7) km).` |
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| 1643. |
For a particle in motion, distance-time graph is shown in figure. From graph answer the following: (i) During which time period the particle is stationary? (ii) Find magnitude of velocity in OA, AB and BC parts. |
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Answer» SOLUTION :(i) From `t = 10 s ` to t = 20 s (II) `3 MS ^(-1) , 0 ms ^(-1) and 2 ms ^(-1)` |
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| 1644. |
How can a spring balance and a rigid rod be used to weigh objects beyond the maximum reading of the balance?Explain |
Answer» Solution :(i) Consider the lever as a force multiplier. (II) Thespring balance and therigid rod are arranged as shown in the figure. (iii) The WEIGHT (W) is SUSPENDED from the rod and reading of the spring balance (R) is noted. (iv)Applying PRINCIPLE of moments,we getweight `xx` distance of weight from the fulcrum = reading `xx` distance of spring balance from thefulcrum. |
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| 1645. |
At which part of the earth must a body be placed so that it will experience the maximum force of attraction? Where the radius is large/where the radius is small? |
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| 1646. |
Why do people prefer wearing white clothes during summer? |
| Answer» Solution :PEOPLE prefer WHITE or light COLOURED CLOTHES during summer as they are good reflectors of heat and hence, they KEEP us cool. | |
| 1647. |
Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it a violation of the law of conservationof energy? |
Answer» Solution : A simple PENDULUM consists of a spherical metal bob suspended by a thread from a rigid supprts. .A. is the mean position of the pendulum. As the bob is displaced to end .C., it GAINS potential energy. As it is released from rest (position .C.), its kinetic energy begins to INCREASE. At the intermediate position .B. the energy is partly kinetic and partly potential. At mean position .A., the energy is totally kinetic. At the end .D. again the energy BECOMES totally potential. The transformation of energy goes on and the pendulum oscillates. Total mechanical energy remains constant at all points. The energy of the pendulum is gradually used in doing work against the force of FRICTION at the point of suspension and also against friction of air. With the passage of time, energy of the pendulum goes on decreasing and finally become zero. So the bob eventually comes to rest. There is no violation of the law of conservation of energy. |
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| 1648. |
A metal cube of side 5 cm and density 7.9gcm^(-3) is suspended by a thread and is immersed completely in a liquid of density 1.1gcm^(-3), Find (a) the weight of cube(b) the upthrust on cube and (c) the tension in thread. (Take g=10ms−2) |
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Answer» Solution :Given side of cube =5cm `:.` volume of the cube `=5xx5xx5=125cm^(3)` `125cm^(3)xx7.9gcm^(-3)` `=987.5g` `:.` WEIGHT of the cube =987.5gf(downwards) b. upthrust on cube = weight of liquid DISPLACED `=` volume of cube `xx` density of liquid `xxg` `=125xx1.1xxg=37.5g` (upwards) c. TENSION in thread =Net downward FORCE `=` Weight of cube - Upthrust on cube `=987.5-137.56=850.0gf` |
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| 1649. |
A ball is thrown vertically upwards with a velocity of 49 m//s. Calulate (i) The maximum height to which it rises, (ii) the total time it takes to return to the surface of the earth. |
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Answer» Solution :Please note that here the ball is going up against the gravity so the value of acceleration due t gravity g is t be takenas negative ( with a minus SIGN) Here,INITIAL velocity of ball u=49 m/s Final velocity of ball v=0(The ball STOPS at top) Acceleration due to gravity `g=-9.8 m//s^(2)`(The ball goes up) AndHeight ,h=? (To be calculated ) Now ,Putting all these values in the formual `v^(2)=u^(2)+2gh` `(0)^(2)=(49)^(2)+2xx(-9.8)xxh` 0=2401-19.6 h 19.6 h= 2401 `h=(2401)/(19.6)` h=122.5 m Thus the maximum height to which the ball rises is 122.5 metres. (ii)We will first calculate the time taken by the ball to reach the HIGHEST point by using the formula : v=u+gt HereFinal velocity v=0(the ball stops at top ) Initial velocity u= 49 m/s Acceleration due to gravity g=`-98. m//s^2` (The ball goes up ) And so putting these value in the above formula ,we get : `0=49 +(-9.8)xxt` 0=49 - 9.8 t 9.8 t =49 `t=(49)/(9.8)` t= 5 s Thus the ball TAKES 5 seconds to reach the highest point of its upwards journey .Please note that ball will take anequal time ,that ,is 5 seconds to reach return to the surface of the earth .In ohter words the ball will take a total time of 5+5 =10 seconds to return to the surface of the earth . |
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| 1650. |
A train starting from rest attains a velocity of 72 km h^(-1)in 5 minute. Assuming that the acceleration is uniform, find (i) the acceleration and (ii) the distance travelled by the train for attaining this velocity. |
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Answer» Solution :`u =0, v = 72 km h ^(-1) = 20 ms ^(-1) and t = 6 ` minute `= 300 s ` `(i) a = ((v-u))/( t) = (20 ms ^(-1) -0 ms ^(-1))/( 300s )= (1)/(15) ms ^(-2)` (II) `2 as = v ^(2) - u ^(2) -0 ` `therefore s = (v ^(2))/(2A)` `= ((20 ms ^(-1)) ^(2))/(2 XX ((1)/(15) ms ^(-2)))` `= (20 xx 20 xx 15)/(2) m = 3000 m = 3 km` The acceleration of the TRAIN is `(1)/(15) ms ^(-2) and ` the distance travelled is 3 km. |
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