Maximum acceleration of the train in which a 50 kg box lying on i

Subject

Physics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

A body falls freely for 10 s. Its average velocity during this journey is (Take, g = 10 ms-2)

  • 100 ms-1

  • 10 ms-1

  • 50 ms-1

  • 5 ms-1


2.

Three projectiles A, B and C are projected at an angle of 30°, 45°, 60° respectively. If RA, RB and RC are ranges of A, B and C respectively, then (velocity of projection is same for A, B and C)

  • RA = RB = RC

  • RA = RC > RB

  • RA < RB < RC

  • RA = RC < RB


3.

The component ofa vector r along X-axis will have a maximum value, if

  • r is along positive X-axis

  • r is along positive Y-axis

  • r is along negative Y-axis

  • r makes an angle of 45° with the X-axis


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4.

Maximum acceleration of the train in which a 50 kg box lying on its floor will remain stationary (Given, coefficient of static friction between the box and the train's floor is 0.3 and g = 10 ms-2)

  • 5.0 ms-2

  • 3.0 ms-2

  • 1.5 ms-2

  • 15 ms-2


B.

3.0 ms-2

Motion is possible when ma ≥ μmg
The maximum static frictional force = μg mg should be equalto force F = ma

                    

∴            F = ma = μg mg

⇒           a = μs g

Here,     μ= 0.3, g = 10 ms-2

              a = (0.3) × 10

 ⇒          a = 3 ms-2


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5.

A 12 kg bomb at rest explodes into two pieces of 4 kg and 8 kg. If the momentum of 4 kg piece is 20 Ns, the kinetic energy of the 8 kg piece is 

  • 25 J

  • 20 J

  • 50 J

  • 40 J


6.

Which of the points is likely position of the centre of mass of the system shown in the figure ?

                      

  • A

  • D

  • B

  • C


7.

Three bodies a ring (R), a solid cylinder (C) and a solid sphere (S) having same mass and same radius roll down the inclined plane without slipping. They start from rest, if vR, vC and vS are velocities of respective bodies on reaching the bottom of the plane, then

  • vR = vC = vS

  • vR > vC > vS

  • vR < vC < vS

  • vR = vC > vS


8.

Variation of acceleration due to gravity (g) with distance x from the centre of the Earth is best represented by (R → Radius of the Earth)


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9.

A spring is stretched by applying a load to its free end. The strain produced in the spring is

  • volumetric

  • shear

  • longitudinal and shear

  • longitudinal


10.

An ideal fluid flows through a pipe of circular cross-section with diameters 5 cm and 10 cm as shown in the figure. The ratio of velocities of fluid at A and B is

              

  • 4 : 1

  • 1 : 4

  • 2 : 1

  • 1 : 2


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