If F denotes force and t time, then in the equation F = at-1 

Subject

Physics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The mass and volume of a body are found to be 5.00 ± 0.05 kg and 1.00 ± 0.05 m 3 respectively. Then the maximum possible percentage error in its density is

  • 6 %

  • 3 %

  • 10 %

  • 5 %


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2.

If F denotes force and t time, then in the equation F = at-1 + bt2, the dimensions of a and b respectively are

  • [LT-4] and [LT-1]

  • [LT-1] and [LT-4]

  • [MLT-4] and [MLT-1]

  • [MLT] and [MLT-4]


D.

[MLT] and [MLT-4]

By the principal of dimensions homogenety

           F = at-1

  [MLT-2] = a [T-1]

∴          a = [MLT-1]

Similarly for b = [MLT-4]

So, [MLT-1], [MLT-4]


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3.

A car moves a distance of 200 m. It covers first half of the distance at speed 60 kmh-1 and the second half at speed v. If the average speed is 40 kmh-1, the value of v is

  • 30 kmh-1

  • 13 kmh-1

  • 60 kmh-1

  • 40 kmh-1


4.

A bus begins to move with an acceleration of 1 ms-2. A man who is 48 m behind the bus starts running at 10 ms-1 to catch the bus. The man will be able to catch the bus after 

  • 6 s

  • 5 s

  • 8 s

  • 7 s


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5.

A particle is moving with constant acceleration from A to B in a straight line AB. If u and v are the velocities at A and B respectively then its velocity at the midpoint C will be

  • u2 + v22u

  • u + v2

  • v - u2

  • u2 + v22


6.

An aircraft is flying at a height of 3400 m above the ground. If the angle subtended at a ground observation point by the aircraft positions 10 s apart is 30°, then the speed of the aircraft is

  • 19.63 ms-1

  • 1963 ms-1

  • 108 ms-1

  • 196.3 ms-1


7.

Two projectiles A and B thrown with speeds in the ratio 1 : 2 acquired the same heights. If A is thrown at an angle of 45° with the horizontal, the angle of projection of B will be

  • 0°6

  • 60°

  • 30°

  • 45°


8.

A particle crossing the origin of co-ordinates at time t = 0, moves in the xy-plane with a constant acceleration a in the y-direction. If its equation of motion is y = bx2 (b is a constant), its velocity component in the x-direction is

  • 2ba

  • a2b

  • ab

  • ba


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9.

A stationary bomb explodes into three pieces. One piece of 2 kg mass moves with a velocity of 8 ms-1 at right angles to the other piece of mass 1 kg moving with a velocity of 12 ms-1. If the mass of the third piece of 0.5 kg, then its velocity is 

  • 10 ms-1

  • 20 ms-1

  • 30 ms-1

  • 40 ms-1


10.

A block at rest slides down a smooth inclined plane which makes an angle 60° with the vertical and it reaches the ground in t1 seconds. Another block is dropped vertically from the same point and reaches the ground in t2 seconds. Then the ratio of t1 : t2 is

  • 1 : 2

  • 2 : 1

  • 1 : 3

  • 1 : 2


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