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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.
| 51. |
A particle of mass m is suspended from a ceiling through a string of length L. The particle moves in a horizontal circle of radius r. Find a. the speed of the particle and b. the tension in the string. Sch a system is called a conical pendulum.A. `(rg)/sqrt(L^(2)-r^(2))`B. `(rsqrtg)/((L^(2)-r^(2))^(1/4)`C. `(rsqrtg)/((L^(2)-r^(2))^(1/2)`D. `(mgL)/((L^(2)-r^(2))^(1/2)` |
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Answer» Correct Answer - B `(F)/(r) = (mg)/(sqrt(L^(2)-r^(2))` |
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| 52. |
A body of mass 8kg lies on a rough horizontal table. It is observed that a certain horizontal force gives the body an acceleration of the body is `16ms^(-2)` . The coefficient of friction is.A. `0.2`B. `0.3`C. `0.4`D. `0.8` |
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Answer» Correct Answer - D `F-f=8xx4=32 `(i) `2F-f=128` (ii) `"Multiplying"` (i) by (ii), we get `2F-2f=64` (iii) Also, (ii)-(iii) gives `f=128-64=64N` `mumg= muxx8xx10=64` or `mu=(64)/(80)=(80)/(100)=0.8` . |
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| 53. |
A rope of mass m is hung from a ceiling. The centre point is pulled down with a vertical force F. The tangent to the rope at its ends makes an angle `alpha` with horizontal ceiling. The two tangents at the lower point make an angle of `theta` with each other. Find `theta` . |
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Answer» Correct Answer - `theta = 2 tan^(-1) [ (1 + (mg)/(F)) "cot"alpha]` |
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| 54. |
A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity ‘ g ’, the reading on the spring balance will beA. 2 kgB. `(4xxg)kg`C. `(2xxg)kg`D. Zero |
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Answer» Correct Answer - D |
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| 55. |
A block `B` is placed on the block `A`.The mass of block `B` is less than the mass of block `A`. Friction exists between the blocks , whereas the ground on which block `A` is placed is taken to be smooth. A horizontal force `F`, increasing linearly with time begins to act on `B`. The acceleration `a_(A)` and `a_(B)` of blocks `A` and `B`, respectively , are plotted against `t`. The correctly plotted graph is A. B. C. D. |
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Answer» Correct Answer - D |
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| 56. |
A body is sliding down an inclined plane having coefficient of friction 0.5. If the normal reaction is twice that of resultant downward force along the inclined plane, then find the angle between the inclined plane and the horizontal . |
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Answer» `mu = 0.5, N =mg cos theta` `N =2F, F =mg (sin theta- mu cos theta)` `N =2mg(sin theta - mu cos theta)` `mg cos theta =2mg (sin theta -mu cos theta)` `cos theta = 2cos theta (tan theta -mu)` `(1)/(2) =tan theta - (1)/(2) rArr theta = 1 rArr theta = 45^(@)` |
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| 57. |
A light container filled with apples is to bed ragged on a rough floor where sliding friction coefficient is 0.35. The rope used for the purpose can bear a maximum of 1100 N tension. Find the angle with the horizontally which one has to pull the rope to carry maximum amount of apples. Also find this maximum amount of apples in kilograms. |
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Answer» Correct Answer - `[(a) 19.3^(@), (b) 3329.5 N]` |
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| 58. |
A block is about to slide down an inclined plane when its inclination to the horizontal is `theta`. If now a 5 kg weight is attached on the block :A. It is still about to slide down the planeB. It will not slide down the plane unless the inclination is increasedC. It will not slide down the plane unless .the inclination is decreased .D. It will never slide down whatever be the inclination |
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Answer» Correct Answer - A |
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| 59. |
A block A is made to move up an inclined plane of inclination`theta` with constant acceleration `a_(0)` as shown in figure. Bob B, hanging from block A by a light inextensible string, is held vertical and is moving along with the block. Calculate the magnitude of acceleration of block A relative to the bob immediately after bob is released. |
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Answer» Correct Answer - `a_(0) "cos"theta` |
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| 60. |
A solid sphere of mass 2 kg is resting inside a cube as shown in fig. The cube is moving with a velocity `vec(v)=(5t hat(i)+2t hat(j))ms^(-1)`. Here t is time in seconds. All surface are smooth. The sphere is at rest with respect to the cube. What is the total force exerted by the sphere on the cube? A. `sqrt(29) N`B. `sqrt(516) N`C. `26 N`D. `sqrt(89) N` |
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Answer» Correct Answer - B `vec(v)=5that(i)+2that(j)` `vec(a)=(dvec(v))/(dt)=5hat(i)+2hat(j)` `vec(F_(1))=mvec(a)=2(5hat(i)+2hat(j))=10hat(i)+4hat(j)` `W=mg=2g=20N` `F=sqrt((10)^(2)+(4)^(2)+(20)^(2))=sqrt(516)N` |
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| 61. |
Assertion: The terms action and reaction in the third law of motion stand for simultaneous mutual force between a pair of bodies. Reason: In this conext action always precede or cause reaction.A. If both assertion and reason are ture and reason is the correct explanation of assertion.B. If both assertion and reason are ture but reason is not the correct explanation of assertion.C. If assertion is ture but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - C Unlike their meaning in ordianary language, action does not precede or cause reaction. Action and reaction act on different bodies simultaneously. |
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| 62. |
Assertion: The familiar equation `mg=R` for a body on a table is true only if the body is in equilibrium. reason: The equality of mg and `R` has no connection with the third law.A. If both assertion and reason are ture and reason is the correct explanation of assertion.B. If both assertion and reason are ture but reason is not the correct explanation of assertion.C. If assertion is ture but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - B The two force `mg` and `R` can be different. For example a body in an aeeceleration lift. The equality of `mg` and `R` has no connection with the third law because two force `mg` and `R` can be different. |
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| 63. |
Assertion: There is no cause-effect relation between action and raction. Reason: Action and reaction are not simultaneous force.A. If both assertion and reason are ture and reason is the correct explanation of assertion.B. If both assertion and reason are ture but reason is not the correct explanation of assertion.C. If assertion is ture but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - C Action and reaction force are simultaneous forces. There is no cause-effect relation between action and reaction. |
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| 64. |
Assertion:On a merry-go-around, all parts of our body are subjected to an inward force. Reason: We have a feeling of being pushed outward the direction of impending motion.A. If both assertion and reason are ture and reason is the correct explanation of assertion.B. If both assertion and reason are ture but reason is not the correct explanation of assertion.C. If assertion is ture but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - B The objective concept of force in physiscs should not be confuesed with the subjective concept of the feeling of force. Both statement are ture. |
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| 65. |
A block A of mass 3kg and another block `B` of mass `2kg` are connected by a light inextensible string as shown in figure. If the coefficient of friction between the surface of the table and A is 0.5 What maximum mass `C` is to be placed on A so that the system is to be in equlibrium .A. `3kg`B. `2kg`C. `1kg`D. `4kg` |
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Answer» Correct Answer - C For equilibrium `f = mum_(B) g ,f = mu (m_(A) +m_(C))g` . |
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| 66. |
A duster weighs `0.5N`. It is pressed against a vertical board with a horizontal force `11N` If the co-efficient of friction is `0.5` the mimmum force that must be applied on the duster parallel to the board to move it upwards is .A. `0.4N`B. `0.7N`C. `6N`D. `7N` |
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Answer» Correct Answer - C `F_(up) = f + mg, f = mu N,N =F` |
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| 67. |
A block of mass m = 1 kg is kept pressed against a spring on a rough horizontal surface. The spring is compressed by 10 cm from its natural length and to keep the block at rest in this position a horizontal force (F) towards left is applied. It was found that the block can be kept at rest if `8 Nle F le 18 N`. Find the spring constant (k) and the coefficient of friction `(mu)` between the block and the horizontal surface. |
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Answer» Correct Answer - k = `130Nm^(-1) ; mu = 0.5 ` |
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| 68. |
A `2 kg` block is pressed against a rough wall by a force `F = 20 N` as shown in figure .Find acceleration of the block and force of friction acting on it .`(Take g = 10 m//s^(2))` A. `4m//sec^(2)` downward, `12N` upwardB. `2m//sec^(2)` downward, `6N` upwardC. `12m//sec^(2)` downward, `4N` upwardD. `8m//sec^(2)` downward, `12N` upward |
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Answer» Correct Answer - A `f_(s) =mu_(s) mg, W gt f_(s),f_(k) =mu_(k) mg, a =(F_("net"))/(m)` . |
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| 69. |
Minimum force required to keep a block of mass 1 kg at rest against a rough vertical wall is P. If a force `P//2` is applied then the acceleration of the block will be : A. `5 m//s^(2)`B. `2.5 m//s^(2)`C. `2 m//s^(2)`D. `0.9 m//s^(2)` |
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Answer» Correct Answer - A |
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| 70. |
In the system show in figure, mass of the block placed on horizontal surface is M = 4 kg. A constant horizontal force of F = 40 N is applied on it as shown. The coefficient of friction between the blocks and surfaces is `mu = 0.5`. Calculate the values of mass m of the block on the incline for which the system does not move . `["sin" 37^(@) = (3)/(5), g = 10 m//s^(2)]` |
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Answer» Correct Answer - `2kg le m le 30 kg ` |
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| 71. |
A cart of mass M has a block of mass m in contact with it as shown in the figure-2.133. The coefficient of friction between the block and the cart is `mu`. What is the minimum acceleration of the cart so that the block m does not fall ? A. ` mu g`B. `g//mu`C. `mu//g`D. `Mmug//m` |
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Answer» Correct Answer - B |
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| 72. |
A body kept on a smooth inclined plane having inclination 1 in x will remain stationary relative to the inclined plane if the plane is given a horizontal accelertion equal toA. `(g)/(sqrt((x^(2)-1)))`B. `(gx)/(sqrt((x^(2)-1)))`C. `(gsqrt((x^(2)-1)))/(x)`D. `sqrt((x^(2)-1))g` |
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Answer» Correct Answer - A `sinalpha=(1)/(x),tanalpha=(1)/(sqrt(x^(2)-1))` `a=g tanalpha=(g)/(sqrt(x^(2)-1))` |
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| 73. |
Three forces start acting simultaneously on a particle moving with velocity, `barv`. These forces are respresented in magnitude and direction by the three sides of a triangle ABC. The particle will now move with velocity A. `vec(v)` remaining unchangedB. less than `vec(v)`C. Greater than `vec(v)`D. `vec(v)` in the direction of the larges force BC |
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Answer» Correct Answer - A Net force on the particle is zero so the `vec(v)` remains unchanged. |
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| 74. |
A small sphere of mass `m =2kg` moving with a velocity `baru = 4hati - 7hatj m//s` colides with a smooth wall and returns with a velocity `barv = -hati + 3hatj m//s`. The magnitude of the impulse received by the ball is .A. `5 kgms^(-1)`B. `10 sqrt5 kgms^(-1)`C. `20 kg ms^(-1)`D. `15 kg ms^(-1)` |
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Answer» Correct Answer - B `J = m(v -u)` |
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| 75. |
The horizontal acceleration that should be given to a smooth inclined plane of angle `sin^(-1)((1)/(l))` to keep an object stationary on the plane relative to the inclined plane is .A. `(g)/sqrt(l^(2)-1)`B. `gsqrt(l^(2)-1)`C. `(sqrt(l^(2)-l))/(g)`D. `(g)/(sqrt(l^(2)+1))` |
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Answer» Correct Answer - A Resolve mg and pseudo force into components At equilibrium `mg sin theta = ma cos theta` . |
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| 76. |
A rope of length `10m` and linear density `0.5kg//m` is lying length wise on a smooth horizontal floor It is pulled by a force of `25N`. The tension in the rope at a point `6m` away from the point of application is .A. `20N`B. `15N`C. `10N`D. `5N` |
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Answer» Correct Answer - C Force on unit length `=(F)/(L),` Force on l units of length ` =((F)/(L))l` Tension at `(L -l)` length `= (F)/(L) (L-l)` . |
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| 77. |
Three forces start acting simultaneously on a particle moving with velocity, `barv`. These forces are respresented in magnitude and direction by the three sides of a triangle ABC. The particle will now move with velocity A. `vec(v)` remaining unchangedB. less than `vec(v)`C. greater than `vec(v)`D. `vec(v)` in the direction of the largest force BC |
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Answer» Correct Answer - A Net force =0 |
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| 78. |
In the fig. mass M=10gm. Is placed on an inclined plane. In order to keep it at rest, he value of mass m will be: A. 5gB. `10sqrt(3)g`C. `0.10g`D. `sqrt(3)g` |
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Answer» Correct Answer - A `Mgxx(1)/(2)=mg` `m=5gm` |
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| 79. |
What force must man exert on rope to keep platform in equilibrium : (Take `g=10m//s^(2)`) A. 100NB. 200NC. 300ND. 500N |
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Answer» Correct Answer - C |
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| 80. |
A stone of mass `m` is tied to a strin and is moved in a vertical circle of radius `r` making `n` revolution per minute. The total tension in the string when the stone is its lowest point is.A. `mg`B. `m(g+pinr^(2)`C. `m(g+nr)`D. `m(g+(pi^(2)n^(2)r)/(900))` |
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Answer» Correct Answer - D The tension at the lowest point is given by `T_(1)=(m)/(r)(v^(2)+gr)` `=m((v^(2))/(r)+g)` `( :. v=romega)` (i) Now `omega=2pif` where f=frequency of revolution. The frequency of revolution per sec, `n=(f//60)` `:. omega=2pin//60=(pin//30)` (ii) From equation (i) and (ii), `T_(1)=m[(r^(2)pi^(2)n^(2))/(900r)+g]` `=m[g+(r^(2)pi^(2)n^(2))//900]` . |
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| 81. |
The keep a particle moving with constant velocity on a frictionless surface, an external force .A. should act continuoslyB. should be a variable forceC. not necessaryD. should act opposite to the direction of motion |
| Answer» Correct Answer - C | |
| 82. |
A body A mass `m_(1)` exerts a force on another body B of mass `m_(2)` . If the acceleration of B be `a_(2)` , then the acceleration (in magnitude) of A isA. ZeroB. `m_(2)a_(2)//m_(1)`C. `m_(1)a_(2)//m_(2)`D. `a_(2)` |
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Answer» Correct Answer - B `F=m_(2)a_(2)=m_(1)a_(1)` `therefore a_(1)=(m_(2))/(m_(1))a_(2)` |
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| 83. |
A body A mass `m_(1)` exerts a force on another body B of mass `m_(2)` . If the acceleration of B be `a_(2)` , then the acceleration (in magnitude) of A isA. `(m_(2))/(m_(1))a_(2)`B. `m_(1)m_(2)a_(2)`C. `(m_(1))/(m_(2))a_(2)`D. `(m_(1)+m_(2))a_(2)` |
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Answer» Correct Answer - A Force on `B=m_(2)a_(2)` :. Force on `A=m_(1)a_(1)` Acceleration of `A=(m_(2)a_(2))/(m_(1)` . |
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| 84. |
Inside a railway car a plumb bob is suspended from the roof and a helium filled balloon is tied by a string to the floor of the car. When the railway car accelerates to the right then.A. both the plumb bob and balloon move the leftB. both the plumb bob and balloon move to the rightC. plumb bob moves to the left and the balloon moves to the rightD. plumb bob moves to the right and the balloon moves to the left |
| Answer» Correct Answer - C | |
| 85. |
A force produces an acceleration of `a_(1)` in a body and the same force produces an acceleration of `a_(2)` in another body. It the to bodies are combined and the same force is applied on the combination the acceleration produced in it is .A. `a_(1)+a_(2)`B. `(a_(1)+a_(2))/(a_(1)a_(2))`C. `(a_(1)a_(2))/(a_(1)+a_(2))`D. `sqrt(a_(1)a_(2)` |
| Answer» Correct Answer - C | |
| 86. |
Assertion : If two objects of different masses have same momentum, the lighter body possess greater velocity. Reason : For all bodies momentum always remains same.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false. |
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Answer» Correct Answer - C |
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| 87. |
Assertion: Two bodies of masses `M` and `m(M gt m)` are allowed to fall from the same height if the air resistance for each be the same then both the bodies will reach the earth simultaneously. Reason: For same air resistance, acceleration of both the bodies will be same.A. If both assertion and reason are ture and reason is a true explanation of assertion.B.C. If assertion is ture but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - D The force acting on the body of mass `M` is its weight `Mg` acting vertically upward. :. Acceleration of the body, `a=(Mg-F)/(M)=g-(F)/(M)` Now, `Mgtm` , therefore, the body with larger mass will have greater acceleration and it will reach the ground first. |
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| 88. |
The two blocks shown in figure-2.200 are initially at rest. Assuming ideal pulleys and strings and neglecting friction at all the surfaces, find the accelerations of the two blocks and the tension in the cable.(Take `g = 9.8m/s^(2)`) |
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Answer» Correct Answer - `[2.49 m//s^(2), 0.831 m//s^(2), 74.8 N]` |
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| 89. |
In the arrangements shown, the pulleys, strings and springs are weightless and the systems can move freely without friction The extension of spring in `1` is `x_(1)` and that in `2` is `x_(2)` Then .A. `x_(1)=x_(2)`B. `x_(2)gtx_(1)gt0`C. `x_(1)gt x_(2) =0`D. `x_(1) gt x_(2) gt0` |
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Answer» Correct Answer - D In figure I Tension `T_(1) = 20g//3`, in figure II Tension `T_(2) =5g` So, `x_(1) gt x_(2) gt0` . |
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| 90. |
A uniform rod of length `L` rests against a smooth roller as shown in Fig. Find the friction coefficient between the ground and the lower end if the minimum angle that the rod can make with the horizontal is `theta`. |
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Answer» Correct Answer - `(L cos theta sin^(2)theta)/(2h-L cos^(2)theta sin theta)` |
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| 91. |
Determine the time in which the smaller block reaches other end of bigger block in figureA. `4 s`B. `8 s`C. `2.19 s`D. `2.13 s` |
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Answer» Correct Answer - C `f =mum_(A)` For smaller block `F -f =m_(A) a_(1)` For larger block `f =m_(B) a_(2)` `a_(rel) =a_(1) -a_(2), s =ut + (1)/(2) at^(2)` . |
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| 92. |
Two fixed frictionless inclined plane making angles `30^(@)` and `60^(@)` with the vertical are shown in the figure. Two blocks A and B are placed on the two planes What is the relative vertical acceleration of A with respect to B ? |
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Answer» `mg sin theta = ma rArr a = g sin theta` where a is along the inclined plane `:.` vertical component of acceleration is `g sin^(2) theta` `a_(r) =a_(AB) =a_(A) -a_(B)` `:.` relative vertical acceleration of `A` with respect to `B` is `g (sin^(2) 60^(0) - sin^(2) 30^(0)) = (g)/(2) =4.9ms^(-2)` (in vertical direction) . |
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| 93. |
Two blocks each of mass M are resting on a frictionless inclined plane as shown in fig then: A. The block A moves down the planeB. The block B moves down the planeC. Both the blocks down the planeD. Both the blocks remains down the plane. |
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Answer» Correct Answer - A Block A has higher value of ` Mg sin theta` |
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| 94. |
Find the least horizontal force P to start motion of any part of the system of the three blocks resting upon one another as shown in figure The weights of blocks are `A = 300 N , B = 100 N` and `C = 200 N` .Between A and B , the coefficient of friction is `0.3` between B and C is `0.2` and between C and the ground is `0.1` A. `60N`B. `90N`C. `80N`D. `70N` |
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Answer» Correct Answer - A `f_(l_(1)) = mu_(1) m_(A) g, f_(l_(2)) = mu_(2) (m_(A)+m_(B))g` `f_(l_(3)) =mu_(3) (m_(A) +m_(B) +m_(C))g` . |
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| 95. |
A person is sitting in a travelling train and facing the engine. He tosses up a coin and the coin falls behind him. It can be concluded that the train isA. Moving forward and gaining speedB. Moving forward and losing speedC. Moving forward with uniform speedD. Moving backward with uniform speed |
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Answer» Correct Answer - A |
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| 96. |
Assertion : Impulse and momentum have different dimensions. Reason : From Newton’s second law of motion, impulse is equal to change in momentum.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If assertion is fa lse but reason is true. |
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Answer» Correct Answer - D |
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| 97. |
The momentum of a system is conservedA. AlwaysB. NeverC. In the absence of an external force on the systemD. None of the above |
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Answer» Correct Answer - C |
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| 98. |
A small body of super dense material, whose mass is half the mass of the earth (but whose size is very small compared to the size of the earth), starts from rest at a height H above the earth’s surface, and reaches the earth’s surface in time t. Calculate time t assuming that H is very small compared to the radius of the earth. Acceleration due to gravity near the surface of the earth is g. |
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Answer» Correct Answer - `sqrt((4H)/(3g))` |
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| 99. |
Two bodies of mass m and 4m are attached by a string shown in the figure-2.146. The body of mass m hanging from a string of length l is executing simple harmonic motion with amplitude A while other body is at rest on the surface. The minimum coefficient of friction between the mass 4m and the horizontal surface must be to keep it at rest is : A. `(1)/(4)(1-(A^(2))/(l^(2)))`B. `(1)/(4)(1+(A^(2))/(l^(2)))`C. `(1)/(4)(A)/(l)costheta`D. `(1)/(4)` |
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Answer» Correct Answer - B |
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| 100. |
A disc of mass m lies flat on a smooth horizontal table. A light string runs halfway around it as shown in figure. One end of the string is attached to a particle of mass m and the other end is being pulled with a force F. There is no friction between the disc and the string. Find acceleration of the end of the string to which force is being applied. |
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Answer» Correct Answer - `(5F)/(m)` |
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