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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Assertion: In a mixture of gases at a fixed temperatue, the heavier molecule has the lower average speed. Reason: Temperature of a gas is a measure of the average kinetic energy of a molecule. |
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Answer» If both assertion and REASON are true and reason is the correct explanation os assertion. |
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| 2. |
A machine gun fires a bullet of mass 50 gram with a velocity of 800 m/s. The man holding the machine gune can exert a maximum force o 200N. What is the maximum number of bullets he can fire per second? |
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Answer» 2 `therefore` Momentum of n bullets/sec `=n(mv)= nxx50xx10^(-3) xx 800= 40n` But by Newton's second LAW F =Rate of change of momentum `therefore 200= 40n therefore n=5` bullets |
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| 3. |
A boy of mass 30kg is running with a velocity of 3 ms^(-1)on ground just tangenti-ally to a merry - go -round which is at rest. It has radius R = 2m, a masss of 120 kg and its radius of gyration is lm. If the boy suddenly jumpes on to the merry -go - round, the angular velocity acquired by the system is |
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Answer» `1 RAD s^(-1)` |
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| 4. |
Rain is falling vertically with a velocity of 4kmhr^(-1) . A cyclist is going along a horizontal road with a velocity of 3km hr^(-1) towards east. Calculate the relative velocity of the rain with respect to the cyclist . In what direction must the cyclist hold his umbrella to save himself from the falling rain? |
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Answer» Solution :The SITUATION is shown in Fig. OA represents velocity `vecv_(c) ` of cyclist , which is `3km hr^(-1)` OB represents velocity `vecv_(R)` of vertically falling rain , which is `4km hr^(-1)`. OC represents `-vecv_(c)` opposite of velocity of the cyclist . OD represents `vecv_(R)+(-vecv_(c))=vecv_(R)-vecv_(C)` velocity of rain relative to cyclist . In parallelogram OBDC. `OC=3km hr^(-1), OB=4km hr^(-1)` `/_BOC=90^(@)` Hence `OD=sqrt((OC)^(2)+(OB)^(2))=sqrt((3)^(2)+(4)^(2))=sqrt(9+16)=sqrt(25)=5 km hr^(-1)` `tan beta =(BD)/(OB)=(OC)/(OB)=3/4=0.75=tan 36^(@)52.`,i.e., `beta=36^(@)-52.`EAST of vertical . the cyclist must hold his umbrella at `36^(@)-52` with vertical in the direction of his motion(i.e. east). 
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| 5. |
In the above, suppose that the smaller ball does not stop after collision, but continues to move downwards with a speed =(upsilon_(0))/(2) after the collision. Then, the speed of each bigger ball after collision is |
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| 6. |
Assertion :The job of asimple pendulum consits of a hollow bal full of water and when a hole is made at the bottom of ballits time period first increases and then decreases Reason:Weight of the ball decreases as water flows out of ut |
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Answer» If the ASSERTION and reason are correct and reason is a correct explanation of the assertion |
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| 7. |
Which of the following statement is untrue? The velocity of sound in a gas ………… |
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Answer» is INDEPENDENT of PRESSURE |
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| 8. |
A rope of length L and mass per unit length lambda passes over a disc shaped pulley of mass M and radius R. The rope hangs on both sides of the pulley and the length of larger hanging part is l. The pulley can rotate about a horizontalaxis passing through its centre. The system is released from rest and it begins to move. The pulley has no friction at its axle and the rope has large enough friction to prevent it from slipping on the pulley. (a) Find the acceleration of the rope immediately after it is released. (b) Find the horizontal component of the force applied by the axle on the pulley immediately after the system is released |
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| 9. |
Can a body in equilibrium while in motion? If yes state an example. |
| Answer» Solution :YES a BODY in MOTION will be in equilibrium and angular acceleration. Hence a body MOVING with uniform velocity ALONG a straight line will be in equilibrium. | |
| 10. |
A bob of mass 100 g tied at the end of a string of length 50 cm is revolved in a vertical circle with a constant speed of 1 ms^(-1). When the tension in the stringis 0.7 N, the anglemade by the string with the vertical is (g = 10 ms^(-2)) |
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Answer» `0^(@)` |
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| 11. |
A metal piece weighing 50g is heated to a temperature of 200^(@)C and is then quickly dropped into a calorimeter of water equivalent 100g containing 150g of water at 20^(@)C. After thorough stirring, the highest temperature of water is recorded as 24^(@)C. Find the specific heat capacity of the metal. (specific heat capacity of water is 4180 "J/kg"-^(@)C) |
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| 12. |
An ideal gas undergoes isothermal process from some initial state I to final state f. Choose the correct alternatives.a) dU=0 b) dQ=0 c) dQ=dU d) dQ=dW |
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Answer» only a,B are correct |
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| 13. |
Three blocks A,B and C are kept as shown in the figure. The coefficient of friction between A and B is 0.2, B and C I s0.1 C and ground is smooth. The mass of A,B and C are 3 kg , 2 kg and 1 kg respectively. A is given a horizontal velocity 10 m/s A,B and C always remains is contact i.e., lies as in figure. The total work done by friction during this process is 25xJ. Then find x. |
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| 14. |
The astronomers used to observe distant points of the universe by ………. |
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Answer» Electron TELESCOPE |
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| 15. |
A satellite in force free spacesweeps stationary interplanetary dust a rate dM/dt = sigmav where M is the mass, V is the velocity of the satellite and alpha is a constant. The acceleration of the satellite is (-alphav^(k))/(M). Find the value of k |
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| 16. |
Name two factors which determine whether aplanet has an atmosphere or not. |
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Answer» Solution :`implies`Two factors are as following: (i) Value of acceleration due to gravity of PLANET. (ii) TEMPERATURE of the SURFACE of the planet. Because speed of molecules of GAS is according to temperature. |
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| 17. |
A pendulum clock is 5 seconds fast at a temperature of 15^(@)C and 10 seconds slow at a temperature of 30^(@)C. The temperature at which it gives the correct time is |
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Answer» `18^(@) C` |
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| 19. |
A 400 kg satellite is in a circular orbit of radius 2R_E about the Earth. How much energy is required to transfer it to a circular orbit of radius 4R_E? |
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Answer» Solution :Initially `E_i=(GM_E m)/(4R_E)` While finally `E_f=-(GM_E m)/(8R_E)` The change in the TOTAL ENERGY is `DELTAE=E_f-E_i` `=(GM_E m)/(8R_R)=((GM_E)/R_E^2)=(mR_E)/8` `DeltaE=(GM R_E)/8=(9.81xx400xx6.37xx10^6)/8=3.13xx10^9` J |
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| 20. |
Human heart pumps 70 cc of blood at each beat against a pressure of 125 mm of Hg. If the pulse frequency is 72 per minute, the power of the heart is nearly |
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Answer» 1.2 W |
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| 21. |
There are certain musical instruments in which sound is produced by vibrations of air column.show that different frequencies produced in a closed organ pipe are in the ratio 1:3:5. |
Answer» SOLUTION :
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| 22. |
If the coefficient of friction is sqrt(3), the angle of friction is |
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Answer» `30^(@)` |
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| 23. |
A stone dropped from the top of a tower of height 300 m high splashes into the water of a pond near the base of the tower. When is the splash heard at the top givne that the speed of sound in air is 340 ms ^(-1) ? (g =9.8 ms ^(-2)) |
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Answer» Solution :(i) If H is the height of a tower and if time taken by stone to fall freely through this height is `t _(1)` then, `t _(1) = sqrt ((2H)/(g)) = sqrt ((2 xx 300)/(9.8)) =7.82s` (ii) Now, if time taken by sound to reach the top of tower from the water pond is `t _(2)` then. `t _(2) = (h)/(v) = (300)/(340) =0.88 s` (iii) Required time, `t _(1) + t _(2) =7.82+0.88 =8.7 s` |
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| 24. |
In a planetary motion the areal velocity of a position vector of a planet depends on angular velocity 'w' and distance of the planet from the sun (r). If so the correct relation for areal velocity |
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Answer» `(d A)/(d t) prop omega r` |
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| 25. |
The time taken by a particle performing SHM on a straight line to pass from point A to B where its velocities are same is 2 seconds. After another 2 seconds it returns to B. The time period of oscillation is in seconds) |
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| 26. |
A spring balance has a scale that reads 0 to 10 kg . The length of the scale is 10cm . A body suspended from this balance , when displaced and released , oscillates with period of (pis)/(10). What is the mass of the body ? (g=10ms^(-2)) |
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Answer» `2.5kg` |
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| 27. |
A uniform rectangular block of mass 50 kg is hung horizontally with the help of three wires A, B and C each of length and area of 2 m and 10 mm^2respectively as shown in the figure. The central wire is passing through the centre of gravity and is made of a material of Young's modulus 7.5 xx 10^10 Nm^(-2)and the other two wires A and C symmetrically placed on either side of the wire B are of Young's modulus 10^11 Nm^(-2) . The tension in the wires A and B will be in the ratio of |
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Answer» `1:3` |
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| 28. |
The following table gives the range of a particle when thrown on different planets. All the particles are thrown at the same angle with the horizontal and with the same initial speed . Arrange the planets in ascending order according to their acceleration due to gravity (g value){:("Planet","Range"),("Jupiter",50 m ),("Earth",75 m ),("Mars",90 m ),("Mercury",95 m ):} |
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Answer» SOLUTION :SINCE,` g prop (1)/("Range")` `g_("jupiter") = (1)/(50) = 0 . 02` `g_("earth")= (1)/(75) = 0 . 0133` `g_("MARS") = (1)/(90) = 0.0111` `g_("MERCURY")= (1)/(75) = 0 . 0 105` `:. g_("mercury") ltg_("mars") lt g_("earth") lt g_("jupiter")` |
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| 29. |
A minimum force F is applied to a block of mass 102 kg to prevent it from sliding on a plane with an inclination angle 30^(@) with the horizontal. If the coefficients ofstatic and kinetic friction between the block and the plane are 0.4 and 0.3 respectively, then the force F is |
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Answer» 157 N `mu , mg COS theta =(0.4)(102)(10) cos 30^(@)` =353 N `F=510-353=157N` |
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| 30. |
(A): No particle many have a speed as large as speed of light. (R ): Infinite energy of any substance or system is not possible. |
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Answer» Both 'A' and 'R' are TRUE and 'R' is the correct explanation of 'A's |
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| 31. |
What is meant by inelastic collision? |
| Answer» SOLUTION :A collision in which only LINEAR MOMENTUM is CONSERVED but not the kinetic energy of the interacting system is CALLED inelastic collision. | |
| 32. |
1kg of an ideal gas expands adiabaticallyfrom 200 K to 250 K. If the specific heat of the gas at constant volume is 0.8 kJ kg^(-1)K^(-1),then the work done by the gas is |
| Answer» ANSWER :D | |
| 33. |
An ideal gas is pumped into a rigid vessel whose walls are diathermic. In a certain time interval thepressure of the gas in the container becomes 4 times, the internal energy will ... in the interval. Best suitable option for the blank space is. |
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Answer» remains CONSTANT |
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| 34. |
Thermal conductivity of coppe is 9 times that of steel. As shown in figure the temperature difference between ends of copper and steel is 100^(@)C. Find the temperature of their contact surface. |
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Answer» `75^(@)C` `K_(c)=9K_(s)` `T_(1)=100^(@)C` `T_(2)=0^(@)C`  Suppose `T_(x)=` TEMPERATURE of contact surface In thermal equilibrium `H_(C)=H_(S)` `:.(K_(c)A(T_(1)-T_(x)))/(L_(1))=(K_(s)A(T_(x)-T_(2)))/(L_(2))` But `L_(1)=18` cm and `L_(2)=6` cm `:.(9K_(s)(100-T_(x)))/(18)=(K_(s)(T_(x)-0))/(6)` `:.3(100-T_(x))=T_(x)` `:.300-3T_(x)=T_(x)` `:.300=4T_(x)` `:.T_(x)=(300)/(4)` `:.T_(x)=75^(@)C` |
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| 35. |
A flywheel makes 120 rpm. Find the angular speed of any point on the wheel and the linear speed of a point 10 cm from the centre of the wheel. |
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| 36. |
Consider two springs with force constants 1 Nm^(-1) and 2Nm^(-1) connected in parallel. Calculate the effective spring constant (k_(p)) and comment on k_(p). |
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Answer» Solution :` k_1 = 1 NM^(-1) , k_2 = 2Nm^(-1)` ` k_p = k_1 + k_2 + Nm^(-1)` `k_p = 1 + 2=3 Nm^(-1)` ` k_p gt k_1 " and " k_p gt k_2` Therefore, the EFFECTIVE spring constant is greater than both `k_1 " and " k_2` |
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| 37. |
A person is spinning with his hands outstretched at the rate of 4 rad s^(-1) When he brings his hands close to the body, he spins at the rate of 16 rad s^(-1). The ratio of M.I. in the two cases successively is |
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Answer» `4:1` |
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| 38. |
A body of mass 5 kg is at rest. Three force F_1=10Ndue North F_2=10Nalong East and F_3 = 10 sqrt2 Nalong N-W act on it simultaneously. The acceleration produced in the body is, |
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Answer» `4MS^(-2)` ALONG north |
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| 39. |
Draw the speed-time graph of a ball dropped from a certain height and bounces back |
Answer» SOLUTION :
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| 40. |
The time taken by a particle performing SHM on a straight line to pass from point A to B where its velocities are same is 2 seconds. After another 2 seconds it returns to B. The time period of oscillation is in seconds) ……... |
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| 41. |
When the angle of projection is 75^@ , a ball falls 10 m short of the target. When the angle of projection is 45^@ , it falls 10 m ahead of the target. Both are projected from the same point with the same speed in the same direction, the distance of the target from the point of projection is |
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Answer» Solution :Let d be the distance of the target from the POINT of projection. `:. (u^2 sin (2xx75^@))/g=d-10 "or " u^2/(2g)=d-10""...(i)` and `:. (u^2 sin (2xx45^@))/g=d+10 "or " u^2/(g)=d+10""...(II)` Divide (i) by (ii) , we get `(d-10)/(d+10)=1/2 " or " d = 30 m` |
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| 42. |
A solid cylinder rolls up an inclined plane of angle of inclination 30^(@). At the bottom of the inclined plane the centre of mass of the cylinder has a speed of 5ms^(-1) How long will it take to return to the bottom ? |
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Answer» Solution :But`a=(gsintheta)/(1+(K^2)/(R^2))` i.e `K=(R^2)/2,a=(2gsintheta)/3` HENCE `0=u-at_a` or `t_a=u/a=(5xx3)/(2xx10xxsin30^(@))=3/2` |
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| 43. |
In the figure of problem 17 if the block starts from rest when R = 5r, what is the reaction of the inner track on the sliding mass at the highest point ? From what height should it fall so that it may exert a force equal to its weight on the track at the highesth point ? |
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| 44. |
(A): The tendency of skidding or overturning is quardrupled, when a cyclist doubles his speed of turning. (R): Angle of bending of a cyclist bicycle increases as velocity of increases. |
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Answer» Both .A. and .R. are true and .R. is the CORRECT EXPLANATION of .A. |
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| 45. |
A solid cylinder rolls up an inclined plane of angle of inclination 30^(@). At the bottom of the inclined plane the centre of mass of the cylinder has a speed of 5ms^(-1) How far will the cylinder go up theplane ? |
Answer» Solution :Given, `v_c=5ms^(-1),theta=30^(@)`  We know that, `v^2=(2gh)/(1+(K^2)/(R^2))` Here K`=(R^2)/2` for a solid cylinder `:.v^2=(2gh)/(1+1/2)=4/3gh" or "H=(3v^2)/(4g)` Taking `g=10ms^(-2),h=(3xx5xx5)/(40)=1.875` `SIN30^(@)=h/l"":.l=h/(sin30^(@))=1.875xx2` l=3.75m |
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| 46. |
Air pressure in a car tyre increases during driving. Explain. |
| Answer» SOLUTION :Volume of à CAR tyre is fixed. During driving temperature of the GAS increases while its volume REMAINS constant. So, according to Gay-Lussac.s law, P `to`T (Constant volume) PRESSURE increases with increases temperature. | |
| 47. |
A wheel starts rotating with an-angular velocity of 2 rad/s. If it rotates with a constant angular acceleration 4 "rad/s"^2 what angle does the wheel rotate through in 2.0 s ? What is the angular speed, after 2.0 s. |
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| 48. |
The moment of the force vecF= 4 hati + 5hatj - 6hatk at (2 , 0 , -3) , about the point (2 , -2 ,-2) , is given by |
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Answer» `- 8 HATI - 4hatj - 7hatk`  Moment of the force is , `vectau = (vecr - vecr_(0)) xx vecF` Here , `vecr_(0) = 2 hati - 2hatj - 2hatk` and `vecr = 2 hati + 0 hatj - 3hatk` `therefore vecr - vecr_(0) = (2 hati +0 hatj - 3hatk) - (2hati - 2hatj - 2hatk) = 0 hati + 2hatj - hatk` `therefore tau = |{:(hati , hatj , hatk) , (0, 2 , -1) , (4 , 5 , -6):}| = -7hati - 4hatj - 8hatk` |
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| 49. |
Two identical bodies of same mass are raised to same heights by two persons X and Y in 10s and 20s respectivel. The work done by |
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Answer» X is GREATER |
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| 50. |
Two small balls A and B, each of mass m are joined rigidly by a light horizontal rod of length L. The rod is clamped at the centre in such a way that it can rotate free about a vertical axis through its centre. The system is rotated with an angular speed omegaabout the axis. A particle P of mass m kept at rest sticks to the ball A as the ball collides with it. The new angular speed of the rod is yomega//3 then value of y. |
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