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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.
| 551. |
In an experiment on determining the velocity of a pulse propagating through a stretched string, the stopwatch should be started and stopped atinstants corresponding to the ones shown in: |
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Answer» Fig 1 and Fig 2 |
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| 552. |
A piece of stone of mass 15.1 g is first immersed in a liquid and it weighs 10.9 gf. Then on immersing the piece of stone in water, it weighs 9.7 gf. Calculate the weight of the piece of stone in air |
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| 553. |
Define : Uniform circular motion |
| Answer» Solution :When an OBJECT moves in a CIRCULAR path with uniform SPEED, its motion is CALLED uniform circular motion. | |
| 554. |
The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why. |
| Answer» SOLUTION :ACCORDING to the universal law of gravitation, TWO objects attract each other with equal force, but in opposite directions. The EARTH ATTRACTS the moon with an equal force with which the moon attracts the earth. | |
| 555. |
Where on the earth does a body experience minimum weight? What is the reason? |
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| 556. |
A vessel contains ice and is in thermal equilibrium at -10^(@)C and is supplied heat energy at the rate of 20 cal s^(-1) for 450 seconds. If the mass of ice is 0.1 kg and due to supply of heat energy, the whole ice just melts find the water equivalent of the vessel. (Take specific heat of ice =0.5 cal g^(-1)""^(@)C^(-1) and specific heat of the vessel is =0.1 cal g^(-1)""^(@)C^(-1). Latent heat of fussion = 80 cal g^(-1) and assume that no heat is transferred to the surroundings) |
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Answer» Solution :(i) The AMOUNT of heat ABSORBED by the ice at `-10^(@)C` to just melt = Q. `rArr""Q_(1)=m_(i)S_(i)Delta t+m_(i)L_(F)"(1)"` The actual amount of heat energy SUPPLIED `=Q = Rxx t"(2)"` `Q=20xx450` cal Then find the amount of heat absorved by vessel `Q_(2)=Q-Q_(1)"(3)"` `Q_(2)=m_(V)S_(V)(Delta T)"(4)"` Find the value `m_(V)` from (4). Now water equivalent `=M=m_(V)S_(V)` (ii) 50 g |
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| 557. |
The energy possessed by an oscillating pendulum of a clock is |
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Answer» KINETIC ENERGY |
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| 558. |
How does the density of material of a body determine whether it will float or sink in water? |
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Answer» and it will SINK if `rho_(s)gtrho_(L)` |
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| 559. |
Complete the table by analysing the graph |
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Answer» From B to C uniform velocity From C to D velocity DECREASES |
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| 560. |
The speed time graph of a body is as shown in Figure. Calculate (i) acceleration of body, (ii) retardation of body, (iii) total distance travelled by the body. |
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Answer» Solution :(i) Acceleration of BODY (from portion `OA`), Fig. `= ("CHANGE in VEL.")/("time taken") = ((10 - 0))/(5) = 2 m//s^(2)`. (ii) Retardation of body (from portion `BC`), Fig. `= ("change in velocity")/("time taken") = ((0 - 10))/(16 - 10) = - 1.67 m//s^(2)`. Total distance travelled = Area under the GRAPH `OABC`, Fig. `= (10 xx 5)/(2) + 10 xx 5 + (10 xx 6)/(2) = 105 m` |
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| 561. |
In a free fall the velocity of a stone is increasing equally ion equal intervals of time under the effect of gravitational force of the earth. Then what can you say about the motion of this stone? Whether the stone is having: |
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Answer» -uniform acceleration Let us try to derive these equations by graphical method.Equations of motion from velocity-time graph:  Graph shows the change in velocity with time for an uniformly accelerated object. The object starts from the point D in the graph with velocity u. Its velocity keeps increasing and after time t it reaches the point B on the graph . The initial velocity of the object =u = OD = EA The final velocity of the object =v=OC = EB Time = t= OE = DA Also from the graph we know that , AB=DC For first equation of motion By definition,acceleration =change in velocity / time =(final velcity -initial velocity ) / time =(OC-OD)/OE=DC/OE a=DC/t DC=AB=at From the graph EB=EA+AB v=u+at ....(1) This is first equation of motion. For second equationof motion From the graph the distance covered by the object during time t is given by the area of quadrangle DOEB s=area of the quad-rectangel DOEB s=area of the rectangle DOEA + area of the triangle DAB =(AE x OE) + (1/2 x AB x DA) `s=ut+1//2 at^2`. ...(2) This is second equation of motion. For Third equation of motion From the graph the distance covered by the object during time t is given by the area of the quadrangleDOEB . Here DOEB is a trapezium . Then s=area of trapezium DOEB =1/2 x sum of length of parallel side x distance betweenparallel sides =1/2 x (OD +BE) x OE s=1/2 x (u+v) x t since a =(v-u)/t or t=(v-u)/a THEREFORE s=1/2 x (v+u) x (v-u)/a `2as=v^2-u^2` `v^2=u^2+2as` ....(3) This is third equation of motion. |
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| 562. |
An empty glass test tube floats vertically in water to a depth of 5 cm. Now, on introducing a 8 cm liquid column into the tube, its depth in water is further increased by 4 cm. Now if the empty test tube is allowed to float vertically in the liquid, 5 cm of the tube is seen in air. Find the total length of the tube. |
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Answer» Solution :Case I : Find the depth of IMMERSION for an empty glass tube in water. Take area of cross section and height of the test tube as 'A' and 'H'. Find the density of test tube in TERMS of 'h' by using the law of floatation. Case II : Take the density of the liquid as `'d_(L)'`. Find the volume of the liquid COLUMN into the tube. Now, find the depth of immersion of test tube in water and also the volume of displaced water. Using the law of floatation, find the density of the liquid. Case III : When empty test tube is allowed to float VERTICALLY in the liquid, find depth of immersion in the liquid from given data. Use law of floatation, then weight of floating body (Test tube) = weight of displaced liquid. `rArrh.A.d_(T.)g=(h-5).A.d_(L).g` (1) Solve equation (1), to find the value of 'h'. |
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| 563. |
The distance of a galaxy from the earth is 5.6 xx 10^(25) m. Assuming the speed of light to be 3 xx 10^8 m s^(-1) find the time taken by light to travel this distance. |
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Answer» Solution :TIME TAKEN `=("Distance travelled")/("speed")` `1.87 xx10^(17)` s |
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| 564. |
20 unit = ……………. Watt-second. (20xx10^(3),3.6xx10^(6),7.2xx10^(7)) |
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| 565. |
There is a four storeyed house in the neighbourhood of Rohan and Amit which has two types of staircases in it. One is a normal, stanting type staircase which is inside the house and the other one is a spiral type (vertical) staircase at the back side of the house. Both the staircases lead from the ground floor to the roof of the house. Rohan and Amit are both students of class IX in different schools. Incidently, they are both of the same weight. Rohan said that a person using slanting staircase inside the house would do morework aganist a certain 'natural force' in goind from ground floor to the roof of the house (because the distance moved by the persin in using the slanting staircase is more). Rohan also said that the work done by the same person aganist the same natural force in going from ground floor to roof of the house would be less by using the spiral type (vertical) staircase (because the distance moved by him in this case will be less). Amit, however, did not agree with Rohan. Amit said that whether this person uses slanting staircase or spiral type (vertical) staircase, work done by him aganist the natural force in goind from ground floor to roof of the house would be the same. Rohan then decided to go from the ground floor to the roof top by slanting staircase and tool 90 seconds for doing this job. On the other hand, Amit went from ground floor to the roof top by spiral type (vertical) staircase and took 2 minutes for this job. (a) Name the natural force aganist which work has to be done in going from ground floor to the roof top of the house. (b) What supplies energy for doing work when Rohan and Amit climb up to the roof of the house? (c) Whose statement about the amount of work doen aganist the natural force in going from ground floor to roof top is correct and why? (d) Who has more power in terms of physics in climbing to roof top: Rohan or Amit? Why? (e) What value are displayed by Amit in this episode? |
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Answer» Solution :(a) The force of gravity. (b) Food supplies the chemical energy for doing work. (c) Amit's statement about the amount of work done against gravity in going from ground floor to roof top is correct. This is because when the work is done against gravity, then the distance moved by the person is the 'vertical distance' through which the person LIFTS himself aganist gravity. And the vertical distance moved up by a person in going from ground floor to roof top of the house is the same whether he uses slanting staircase or SPIRAL TYPE staircase. DUE to this, the work doen by the person aganist gravity in both the CASE is the same. (d) Rohan does the work of going from ground floor to roof top in 90 seconds whereas Amit does the same amount of work in 2 minutes or `2 xx 60 = 120` seconds. Since Rohan takes lesser time (of 90 seconds) to do the same work, so the rate of doing work (or power) of Rohan is more than that of Amit. (e) The valuesdisplayed by Amit in this episode are (i) Awareness of the force of gravity (ii) Correct knowledge of the work done aganist gravity, and (iii) Application of knowledge in solving everyday problems. |
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| 566. |
How are the wave length and freque ncy of a sound waverelated to its speed ? |
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Answer» Speed `(UPSILON)-"Wave length " (lambda) "x Frequency"(v)` `v=lambda x v` |
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| 567. |
A stone is thrown vertically upwards with an initial velocity of 40 m/s. Taking g=10m//s^(2) find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone. |
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Answer» Solution :According to the eqution of motion under gravity, `v^(2)-u^(2)=2gs` Where v=final velocity of the STONE=o u=Initial velocity of the stone =40m/s s=Height of the stone g=Acceleration due to gravity `=-10ms^(2)` Let h be the maximum height attained by the stone. Therefore, `o-(40)^(2)=2xxhx(-10)` `h=40xx40//20=80m` Therefore, TOTAL DISTANCE covered by the stone during its upward and downward journey `=80+80=160m` Net displacement of the stone during its UPWARDS and DOWNWARDS journey. `=80+(-80)=0` |
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| 568. |
You are given a resistance wire AB connected with a cell and a key as shown in Fig. 9.14.You are required to measure the current in the wire AB and potential difference across it. Name the instruments that you would use and draw a labelled diagram to show how are they connected, Also mark the direction of current in each component. |
Answer» Solution : To measure current, an AMMETER is used and to measure the POTENTIAL DIFFERENCE, a VOLTMETER is used. The ammeter (A) is connected in series with the resistance wire AB and cell, while the voltmeter (V) is connected in parallel across the wire AB. Care is taken that + marked terminal of ammeter (A) and voltmeter (V) is joined to the side of + ve terminal of cell. The completed diagram is given below in Fig. 2. The arrow marked in the diagram shows the DIRECTION of current. 
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| 570. |
From a rectangular sheet EFGH of metal, two small square shaped pieces, as shown in the figure, are removed. The remaining metal sheet is then heated. What happens to the area of the empty squares ABCD and PQRS? Also explain, what happens to (i) the distance between the points C and D and (ii) the distance between point C and S. |
| Answer» SOLUTION :Is the expansion of the metallic sheet UNIFROM ? If so, how is its length and breath affected ? Recall the formula for AREA of a SQUARE. | |
| 571. |
Mass and weight of a body is determined at the pole and at the equator Is there any difference in the mass? |
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| 572. |
Which type of motion is described by a graph in figure? |
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Answer» UNIFORM motion |
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| 574. |
(a) Complete the diagram to show how a concave mirror forms the. image of the object. (b) What is the nature of the image? |
Answer» SOLUTION :(a)  (B) MAGNIFIED, REAL and INVERTED. |
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| 575. |
Define Electric potential. |
| Answer» SOLUTION :Electric potential is a measure of WORK done on UNIT POSITIVE charge to bring it to that point against all electrical forces. It is represented as .V.. | |
| 577. |
A solid weighs 1.5 kgf in air and 0.9 kgf in a liquid of density 1.2xx10^(3)kgm^(-3). Calculate R.D. of solid. |
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| 578. |
A bullet fired from a gun can pierce through a thick wooden board but the same bullet thrown with a blow of hand can't pierce in the board. |
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Answer» Solution :Because, the velocity v of a bullet fired from the GUN is too much. Hence as per `E_(K)propv^(2)`, (`because` m = constant) the kinetic energy `E_(k)` of the bullet is too much. As a result it can PIERCE through the thick wooden board. While the velocity v of the bullet THROWN by blow of hand is LESS. Hence as per `E_(k)propv^(2)`, kinetic energy of bullet is less. As a result it cannot pierce in the board. |
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| 579. |
Flash of lightning reaches us earlier than the sound of thunder. Explain the reason. |
| Answer» SOLUTION :Light travels much FASTER than SOUND | |
| 580. |
A rectangle glass wedge (prism) is immersed in water as shown in figure E-a. For what value of angle alpha, will the beam of light, which is normally incident on AB, reach AC entirely as shown in figure E-b. Take the refractive index of water as 4/3 and the refractive index of glass as 3/2. |
Answer» Solution :From the geometry of figure E-b it is clear that, the angle of incidence on the side BC is equal to `alpha` (dotted line is a normal DRAWN at the point of incidence). The ray should undergo total internal reflection to REACH AC. For occurrence of total internal reflection, the value of `alpha` must be greater than the critical angle at interface of WATER and GLASS.  Let .C. be the critical angle of interface of glass and water. From the GIVEN condition `alpha gt C .......(1)` We know, `sin C=1/(n^(12))` ........(2) `n_(12)=3/2 / 4/3=9/8` From equation 2, we get `sin C=8/9 rArr C=62^(@)30^(1)` Hence `alpha` is greater than `C=62^(@)30^(1)` Let us see few activities of total internal reflection. |
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| 581. |
In momentum of the object having mass 4kg is 20kgms^(-1), what would be its kinetic energy? |
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Answer» `25J` |
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| 582. |
A stone is released from the from the top of a tower of height 19.6m calculate its final velocity just before touching the ground. |
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Answer» Solution :According to the equation of motion under GRAVITY. `v^(2)-u^(2)=2gs` Where, u=Initial VELOCITY of the stone=o v=Final velocity of the stone s=Height of the stone =19.6m g-Acceleration DUE to gravity `=9.8ms^(-2)` Therefore `v^(-2)-o^(2)=2xx9.8xx19.6` `V^(2)=2xx9.8xx19.6=(19.6)^(2)` `V=19.6ms^(-1)` Hence, the velocity of the stone just before TOUCHING the ground is `19.6ms^(-1)`. |
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| 583. |
In an high jump athletic event why are athletes made to fall either on a cushioned bed or on a sand bed ? |
| Answer» SOLUTION :In a high jump athletic EVENT ,ATHLETES are made to fall either on a CUSHIONED bed or on as and bed so as to increase the time of the athlete fall to stop after making the jump. This decreases the RATE of change ofmomentum and hence the force. | |
| 584. |
The direction opposite to the movement of electron is called………..current. |
| Answer» SOLUTION :CONVENTIONAL | |
| 585. |
Does the transfer of energy take place when you push a huge rock with all your night and fail to move it? Where is the energy you spend going? |
| Answer» Solution :When we PUSH a huge ROCK, there is no transfer of MUSCULAR energy to the stationary rock. Also, there is no loss of energy because muscular energy is transferred into heat energy which CAUSES our body to become hot. | |
| 586. |
Name the principle which gives the magnitude of buoyant force acting on an object immersed in a liquid |
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| 587. |
Why are sirens of mills heard upto longer distance in the rainy season as compared to the summer season ? |
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Answer» Solution :(i) Factors AFFECTING VELOCITY of sound in AIR . (II) Recall the factor that affects the velocity of sound in air . Out of rainy and SUMMER seasons , in which season the humidity of air is higher ? |
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| 588. |
When a stone falls, it attract the earth just as the earth attracts the stone. But it is only the stone that falls, the earth does not rise up. Give reason? |
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| 589. |
5 tubelights each of 40 W are operated by 10 hour. Calculate electrical energy consumed in 'unit'. |
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| 590. |
What is the relation between centripetal force and centripetal acceleration ? |
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| 591. |
According to Cartesian sign convention, which mirror and which lens has negative focal length? |
| Answer» SOLUTION :Concave MIRROR is having N negative FOCAL length. | |
| 592. |
A container is filled with two immiscible liquids A and B of densities "2 g cm"^(-3) and "3 g cm"^(-3) , respectively. A wooden cube of side 1 cm floats on the surface of liquid A such that one-fourth of its total length is immersed in this liquid (A). Now, the wooden cube is completely immersed in liquid A by suspending a sinker of volume "10 cm"^(3) which is completely submerged in liquid B. Determine the weight of the sinker. |
| Answer» Solution :Apparent weight of the SINKER = EXTRA UPTHRUST. | |
| 593. |
Does the velocity of an object moving with a uniform speed alonga circular path change ? |
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| 594. |
Calculate the mass of a body whose volume is 2 m^3and relative density is 0.52 |
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| 595. |
How do the following factors affect, if at all, the speed of sound in air: Temperature of air |
| Answer» Solution : Speed of SOUND INCREASES with the INCREASE in TEMPERATURE | |
| 596. |
When do we say that work is done? |
| Answer» Solution :WORK is SAID to be done when a force acts on an object and the object MOVE in the direction of force. | |
| 597. |
Acronym of SONAR is_______. |
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| 598. |
Which attractive force between the molecules is responsible for the surface tension? |
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| 599. |
The original name given to the radiations emitted by radioactive substances is ______rays. |
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