A particle is moving uniformly in a circular path of radius r. Wh

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Consider three vectors A = i^ + j^ - 2k^B = i^ - j^ + k^ and C = 2i^ - 3j^ + 4k^. A vector X of the form αA + βB (α and β are numbers) is perpendicular to C. The ratio of α and β is

  • 1 : 1

  • 2 : 1

  • − 1 : 1

  • 3 : 1


2.

In which of the following pairs, the two physical quantities have different dimensions ?

  • Planck's constant and angular momentum

  • Impulse and linear momentum

  • Moment of inertia and moment of a force

  • Energy and torque


3.

A cricket ball thrown across a field is at heights h1 and h2 from the point of projection at times t1 and t2 respectively after the throw. The ball is caught by a fielder at the same height as that of projection. The time of flight of the hall in this journey is

  • h1t22 - h2t12h1t2 - h2t1

  • h1t12 + h2t22h2t1 + h1t2

  • h1t22 + h2t12h1t2 + h2t1

  • h1t12 - h2t22h1t1 - h2t2


4.

A wooden block is floating on water kept in a beaker. 40% of the block is above the water surface. Now the beaker is kept inside a lift that starts going upward with acceleration equal to g/2. The block will then

  • sink

  • float with 10% above the water surface

  • float with 40% above the water surface

  • float with 70% above the water surface


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5.

A smooth massless string passes over a smooth fixed pulley. Two masses m1 and m2, (m1 > m2) are tied at the two ends of the string. The masses are allowed to move under gravity starting from rest. The total external force acting on the two masses is

  • (m1 + m2) g

  • m1 - m22m1 + m2 g

  • (m1 − m2) g

  • m1 + m22m1 - m2 g


6.

To determine the coefficient of friction between a rough surface and a block, the surface is kept inclined at 45° and the block is released from rest. The block takes a time t in moving a distance d. The rough surface is then replaced by a smooth surface and the same experiment is repeated. The block now takes a time t/2 in moving down the same distance d. The coefficient of friction is

  • 3/4

  • 5/4

  • 1/2

  • 1/2


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7.

A particle is moving uniformly in a circular path of radius r. When it moves through an angular displacement θ, then the magnitude of the corresponding linear displacement will be

  • 2r cos θ2

  • 2r cot θ2

  • 2r tan θ2

  • 2r sin θ2


D.

2r sin θ2

In AOB sin θ2 = ABAO      [ AO = r]AB = AO sin θ2   AB = r sin θ2AC = AB + BC                [ AB = BC]      = r sin θ2 + r sin θ2AC = 2r sin θ2So, the magnitude of the corresponding linear displacement will be 2r sin θ2.


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8.

A uniform rod is suspended horizontally from its mid- point. A piece of metal whose weight is w is suspended at a distance l from the mid-point. Another weight w1 is suspended on the other side at a distance l1 from the mid-point to bring the rod to a horizontal position. When w is completely immersed in water, w1 needs to be kept at a distance l1 from the mid-point to get the rod back into horizontal position. The specific gravity of the metal piece is

  • ww1

  • wl1wl - w1l2

  • l1l1 - l2

  • l1l2


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9.

A particle moves with constant acceleration along a straight line starting from rest. The percentage increase in its displacement during the 4th second compared to that in the 3rd second is

  • 33 %

  • 40 %

  • 66 %

  • 77 %


10.

An artificial satellite moves in a circular orbit around the earth. Total energy of the satellite is given by E. The potential energy of the satellite is 

  • - 2E

  • 2E

  • 2E3

  • - 2E3


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