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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.
| 152. |
Find the length of a second.s pendulum at a place where g=10 ms^(-2) (Take pi = 3.14) |
| Answer» SOLUTION :1.0142 m | |
| 153. |
A boy measures the length of a piece of pencil by metre rule, vernier callipers and screw gauge to be 1.2 cm, 1.24 cm and 1.243 cm respectively. Statethe least count of each measuring instrument |
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Answer» Solution : LEAST count of metre rule = 0.1 CM Least count of VERNIER callipers = 0.01 cm Least count of SCREW GAUGE = 0.001 cm |
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| 154. |
A boy measures the length of a piece of pencil by metre rule, vernier callipers and screw gauge to be 1.2 cm, 1.24 cm and 1.243 cm respectively. State the accuracy in each measurement . |
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Answer» SOLUTION :ACCURACY in 1.2 CM = 0.1 cm Accuracy in 1.24 cm = 0.01 cm Accuracy in 1.243 cm = 0.001 cm |
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| 155. |
How much boiling water at 100^@C Is needed to melt 2 kg of ice is that the mixture which is all water is at 0^@C?[Specific heat capacity of water = 4.2 JK^(-1) and specific latent heat of ice = 336 Jg^(-1) ] |
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Answer» Solution :Given , mass of ICE =2 kg = 2000 G . Let m be themass of boiling water required Heat lost =Heat GAINED `m xx c xx Deltat =mxxL` m x 4.2 x (100-0) = 2000 x 336 `m=(2000xx336)/(4.2xx100)` =1600 g or 1.6 kg |
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| 156. |
The distance of a star from the earth is 8.33 light minutes.' What do you mean by this statement ? Express the distance in metre. |
| Answer» SOLUTION :`1.5xx10^(11)` m | |
| 157. |
Ravi filled two cylinders with two gases (X and Y) of equal masses such that under similar conditions of temperature and pressure they occupy volumes of 2 l and 50 l , respectively . If he produces sound through both the gases inside the cylinders , then in which gas does sound travel with greater velocity ? Explain (Given that the value ofgamma is same for both the gases |
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Answer» Solution :Given , temperature and PRESSURE of two gases are similar when equal of gases are taken . Let the volume of 1st gas be `V_(X) = 2l` Let the volume of 2nd gas be `V_(Y) = 50 l` If sound waves are passed through both the gases , SPEEDS of sound waves depends only on the density of gases (SINCE temperature and pressure are similar ). `therefore S alpha (1)/(sqrtd) implies (S_(X))/(S_(Y)) = sqrt((d_(Y))/(d_(X))) ` `(S_(X))/(S_(Y)) = sqrt((m)/(V_(Y)) XX (V_(X))/(m)) ("since"d = (m)/(v))` `(S_(X))/(S_(Y)) = sqrt((2)/(50)) = 1 :5 , (S_(X))/(S_(Y)) = (1)/(5)` `S_(Y) = 5. S_(X)` Speed of a sound waves in gas 'y' is 5 TIMES that in gas 'x'. |
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| 158. |
Using a horizontal force of 200 N , we intend tomove a wooden cabinet across floor at a constant velocity . What is the friction force that will be exerted on the cabinet ? |
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Answer» Solution :The CABINET will MOVE with CONSTANT velocity only when the NET force on it is zero. Therefore , force of FRICTION on the cabinet =200 N , in a direction opposite to the direction of motion of the cabinet . |
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| 159. |
If a fresh egg is put into a beaker filled with water, it sinks On dissolving a lot of salt in the water, the egg begins to rise and then floats. Why ? |
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| 160. |
Calorie is the unit of _____ |
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Answer» HEAT |
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| 161. |
Two objects, each ofmass 1.5 kg are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 ms^(-1) before the collision during which they stick together. What will be the velocity of the combined object after collision ? |
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Answer» Solution :MASS of one of the object , `m_1= 1.5 kg`. Mass of the other object `m_2=1.5 kg `. VELOCITY of `m_1` before collision `u_1=2.5 m//s` velocity of `m_2` moving in OPPOSITE direction before collision, `u_2=2.5 m//s`. Let V be the velocity of the COMBINED object after collision . By thelaw of conservation of momentum. Total momentum after collision =Total momentum before collision . or `(m_1+m_2)=V=m_1u_1+m_2u_2` `(1.5 +1.5)v=1.5xx2.5 +1.5xx(-2.5)` [negative sign as moving in opposite direction ] or `v=O ms^(-1)` |
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| 162. |
Give reasons When a bullet is fired from a gun, the gun recoils. |
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| 163. |
Two copper spheres of equal mass, one solid and the other hollow, are heated through an equal rise in temperature. What is the ratio of the time taken to heat them if the ratio of the rate at which heat is upplied to the solid sphere to hollow sphere is 1:2 ? |
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Answer» Solution :(i) Given that the two spheres are of same material and have equal mass. `rArr"the density "(rho)` and mass (m) of the spheres is constant. Equal rise in temperature `rArr Delta theta ` is constant. RATE of heat supplied (K) `=("Heat supplied (Q)")/("time (t)")` `rArr""Q=Kt"(1)"` `"Also "Q=ms Delta theta"(2)` where 's' is the SPECIFIC heat capacity (in this case it is same for both the spheres) EQUATE (1) and (2) and apply it for both the spheres. From the equations applied find the ratio of time TAKEN to heat spheres. (ii) 2:1 |
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| 164. |
Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term work. ** Suma is swimming in a pondA donkey is carrying a load on its back. A wind mill is lifting water from a well A green plant is carrying out photosyn thesis An engine is pulling a train Food grains are getting dried the sun. A sail boat is moving due to wind energy. |
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Answer» Solution :Work is done whenever the given two conditions are satisfied. A force acts on the body. There is a displacement of the body by the application of force in or oppsite to the direction of force. (a) While swimming, suma applies a force to push the water backwards. Therefore, suma swims in the forward directions caused by the forward REACTION of water. Here the force causes a displacement. Hence is done by seems while swimming. While carrying a load, the donkey has to apply a force in the upward direction. But, displacement of the load in the forward direction since displacement is perpendicular to force, the work done is zero. A wind mill WORKS against the gravitational force to lift water. Hence work is done by the wind mill in lifting water from the well. In this case, there is on displacement of the leaves of the plant. Therefore, the work done is zero. An ENGINE applies force to PULL the TRAIN. This allows the train to move in the direction of force. Therefore, there is a displacement in the train in the same direction. Hence work is done by the engine on the train. Food grains do not move in the presence of solar energy. Hence, the work done is zero during the process of food grains getting dried in the sun. Wind energy applies a force on the sail boat to push it in the forward direction. Therefore there is a displacement in the boat in the direction of force. Hence, work is done by wind on the boat. |
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| 165. |
The brakes applied to a car produce an acceleration of 6 ms^(-2)in the opposite direction to the motion. If the car takes 2 s to stop after the application of brakes, calculate the distance traveled during this time. |
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Answer» Solution :We have been given `a=-6ms^(-2)`, t=2s and v=0 From the equation of motion, v=u+at 0=u+(-6 X 2 ) 0= u -12 `therefore u=12 MS^(-1)` `s=ut+1//2 at^2` `=(12 xx 2) +1//2 (-6 xx 2 xx 2)` =24-12 = 12 m Thus, the CAR will move 12 m before it STOPS after the application of brakes . |
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| 166. |
A student is given an iron cube of side 1cm, a measuring cylinder of range 100 mL and least count 1 mL, and a spring balance of range 100g wt and least count 1g wt. He can use these to measure: |
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Answer» both the MASS and the VOLUME of the GIVEN IRON CUBE |
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| 167. |
A stone is allowed to fall form the top of a tower 100m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s calculate. When and where the two stones will meet. |
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Answer» Solution :Let t be the point at which two stones meet and let H be their height from the ground. It is given in the equation that height of the tower is h=100m. Now first consider the STONE which falls from the top of the tower. So distance covered by this stone at time .t. can be calculated using equation of motion. `X-X_(o)=u_(o)t+3//2g"t^(2)` Since initial velocity U=o so we GET `100-x=1//2g""t^(2)""(1)` The distance covered by the same that is thrown in upwards direction from ground is `x=25t-1//2g""t^(2)""(2)` Adding equation 1 and 2 we get t=4s Putting value to eqn (2) `X=25xx4-1//2xx9.8xx(4)^(2)=100-78.4` =21.6m |
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| 168. |
When is the work done by a force zero? |
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Answer» Solution :If the displacement of the OBJECT is perpendicular to the direction of FORCE, the work done by the force is ZERO. If force is applied on an object but its displacement is zero then also work done by the force is zero. |
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| 169. |
A current of 1.5 A flows through a conductor for 2.0 s. What amount of charge passes through the conductor ? |
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| 170. |
What do the following distance-time graphs indicate ? |
| Answer» Solution :The graph (a) indicates that the object is STATIONARY. The graph (B) indicates that the object is moving with UNIFORM speed. The graph (C) indicates that the object is moving with non-uniform speed. | |
| 171. |
A racing car has a uniform acceleration of 4 ms^(-2). What distance it covers in 10 s after the start ? |
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Answer» Solution :Given : acceleration = `4ms^(-2)` TIME = 10s and initial velocity =0 Formula : `s=ut+1//2 at^2` distance covered `s=0 XX t + 1//2 xx 4ms^(-2) xx (10s)^2` `s=1//2xx4 ms^(-2) xx 100 s^2` =1/2 x 400 m =200 m |
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| 172. |
A pair of bullocks exerts a force of 140N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field? |
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Answer» Solution :Work done = Force `xx` displacement W = F `xx` d Where, F = 140 N therefor W = 140 `xx` 15 d = 15M = 2100 J HENCE, 2100 J of work is done in ploughing the length of the field |
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| 174. |
What happens when cathode rays are subjected to a strong electric field ? |
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| 175. |
How does the speed of sound change with change in wavelength of sound wave ? |
| Answer» SOLUTION :No CHANGE | |
| 177. |
What happened to the water level in the capillary tube? |
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| 178. |
What is the relation between the diameter of capillary tube and capillary rise? Why? |
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| 179. |
At a time when it is cloudy. there may be frequent thunder and lightning. The sound of thunder takes some time to reach you after you see the lightning . Can you answer why this happens ? |
| Answer» Solution :The speed of LIGHT is MUCH more than that of a sound, Therefore, lightning is seen first and the thunder is heard afterwards eventhough both occur at the same TIME. | |
| 180. |
A weather forcecasting plastic balloon of volume 15m^(3) contains hydrogen of density 0.09kgm^(-3). The volume of an equipment carried by the balloon is negligible compared to its own volume. The mass of empty balloon alone is 7.15 kg. The balloon is floating in air of density 1.3kgm^(-3). Calculate (i) the mass of hydrogen in the balloon. (ii) the mass of hydrogen and balloon, (iii) the total mass of hydrogen, balloonand equipment if the mass of equipment is x kg. (iv) the mass of air displaced by balloon and (v) the mass of equipmentusing the law of floatation. |
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| 181. |
A pebble thrown vertically upwards with an initial velocity 50 m s^(-1)comes to a stop in 5 s. Find the retardation. |
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Answer» Solution :GIVEN u = 50 `m s ^(-1) v=0 , t=5 s ` Acceleration a = `(v-u ) /(t) = (0-50 m s^(-1))/(5s)` `= - 10 m s^(-2)` Hence RETARDATION = 10 m `s^(-2)` . |
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| 182. |
Which one of the following liquids has the highest density? |
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Answer» WATER |
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| 183. |
The leastcounts of a vernier calipers and ascrew gaugeare in theratio of 5: 1 . Themainscales ofboth theinstruments are marked in mm. Thezeroerroron thevernier calipers is+0.15 mm where as that onscrewgauge is -0.06 mm. If thediameter of arod lies between 0.9 cm and1.0cm and x and y arethe VCDand CSR onthe twoinstrumentsrelation betweenx and ygiventhat thenumberof C.S.D = 100 is |
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Answer» `x-5y =9` Leastcount ofverniercalipers`=5xx 0.01 =0.05 mm` Let d be thediameterof the ROD `9 mmlt d lt 10 mm` `d=9+ y xx 0.01 +0.06 ` by SCREW GAUGE ` 5x -15 =y+6` `5x -y =21` |
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| 184. |
Observe the motion of a car as shown in the figure and answer the following questions : Compare the distance covered by the car through the path ABC and AC. What do you observe? Which path gives the shortest distance to reach D from A? Is it the path ABCD or the path ACD or the path AD? |
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Answer» SOLUTION :1.AB+BC ABC=4m+3m=7m AC=5 m 2.AB+BC+CD ABCD=4 m+ 3m + 4m =11 m ACD=AC+CD=5 m +4m =9 m AD=3 m `therefore` The shortest distance to REACH D from A will be AD, that is 3 m . |
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| 185. |
What is the nature of the distance-time graphs for uniform and non-uniform motion of an object? |
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Answer» SOLUTION :The distance-time graph for uniform MOTION is a straight line INCLINED with the time AXIS. The distance-time graph for non-uniform motion is a curved line. |
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| 186. |
Name the sounds of the frequencies given below: 40 Hz |
| Answer» SOLUTION :ULTRASONIC | |
| 187. |
A bullet of mass 20 g is horizontally fired with a velocity 150 m/s from a pistol of mass 2 kg . What is the recoil velocity of the pistol ? |
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Answer» SOLUTION :Bullet `m_1` mass =20G =0.02 kg `u_1=0` `v_1 =150m//s` PISTOL `m_2 =2 kg ` `u_2=0` `v_2=?` Total MOMENTUM of the pistol and bullet before firing, when the gun is at rest `=m_1u_1+m_2u_2` `=(0.02 xx0)+(2xx0)` Total momentum of the pistol and bullet after it is fires. `=m_1v_1+m_2v_2` `=(0.02xx150)+(2xxv)` `=3+2 v` Therefore Total mementum after firing = Total moment before firing 3+2v=0 V=-3/2 =-1.5 m/s |
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| 188. |
In rainy season flashes of lightning is seen at first, but the sounds piercing the sky are heard afterwards. |
| Answer» Solution :VELOCITY of flashes of lightning, 1.e., velocity of light is `3 xx 10 ^(8) ms ^(-1),`while velocity of sounds PIERCING sky, i.e., velocity of SOUND is `340 ms ^(-1).`Hence velocity of light is `10^(6)` times the velocity of sound. So light reaches EARTH earlier than sound. | |
| 189. |
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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| 190. |
What is the SI unit of acceleration ? |
| Answer» SOLUTION :The SI unit of acceleration is `m//s^(2) (MS^(-2)).` | |
| 191. |
Find the momentum of a body of mass 100 g having kinetic energy 500 J. |
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Answer» <P> `E_(k)=(1)/(2)m U^(2)` `therefore 500=(1)/(2)xx0.1xxu^(2)` `therefore u^(2)=(500xx2)/(0.1) therefore u^(2)=100 therefore u=10ms^(-1)` Now, momentum `p=m u=0.1xx10` `=1kgms^(-1)` |
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| 192. |
What is the quantity which is measured by the area occupied below the velocity-time graph ? |
| Answer» Solution :The area occupied below the VELOCITYTIME graph SHOWS the magnitude of DISPLACEMENT COVERED by the object in the GIVEN time interval. | |
| 193. |
If you want to lift the water to damp ahainst the force of gravity what is the energy used by motor. Given the mass = 20 kg , Height = 20 ms, Gravity = 9.8 m/s, time 20 min |
| Answer» Solution :WORK DONE by the motor against the gravity W = mgh = 20 `xx` 9.8 `xx` 20 = 3920 J. POWER delivered by the motor = w/t = 3920/ (20 `xx` 60) = 3.27 J/S. | |
| 194. |
Complete the following sentence : Sound can not travel through ......………..,but it requires a ………………….. |
| Answer» SOLUTION : VACUUM, MEDIUM | |
| 195. |
A student heats some amount of tap water in a calorimeter to a temperature of nearly 50^(@)C above the room temperature. He then records the temperature of this water as it is cooling down at regular intervals of 2 minutes each. He tabulates his observations as follows: {:("Time"("in minutes")rarr,0,2,4,6,8,10),("Temperature"("in".^(@)C)rarr,t_(1),t_(2),t_(3),t_(4),t_(5),t_(6)):} He is likely to observe that: |
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Answer» `(t_(1)-t_(2)) GT (t_(3)-t_(4)) gt (t_(5)-t_(6))` |
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| 196. |
Take a toy car. Wind it using its key. Place the car on the ground. Did it move ? |
| Answer» SOLUTION :The TOY CAR MOVES on the GROUND. | |
| 197. |
A solid iron ball of mass 500 g is dropped in mercury contained in a beaker. Will the ball float or sink? Give reasons. |
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| 198. |
Name the constituents of a cell. |
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| 199. |
What type of wave is represented: (a) by density-distance graph? (b) by displacement-distance graph? |
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| 200. |
Which is the solvent in the following binary solutions? (i) sugar and water, (ii) 70 mL of alcohol and 30 mL water, (iii) soda water. |
| Answer» Solution :(i) WATER, (II) ALCOHOL, (III) water (`CO_(2)` is solute) | |