Subject

Physics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Which one of the following represents the correct dimensions of the coefficient of viscosity?

  • ML−1 T−2

  • MLT−1

  • ML−1 T−1

  • ML−1 T−1

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2.

A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to

  • x2

  • ex

  • x

  • x

493 Views

3.

A ball is released from the top of a tower of height h metres. It takes T seconds to reach the ground. What is the position of the ball in T/3 seconds?

  • h/9 metres from the ground

  • 7h/9 metres from the ground

  • 8h/9 metres from the ground

  • 8h/9 metres from the ground

267 Views

4. If space straight A with rightwards arrow on top space straight x space straight B with rightwards arrow on top space equals space straight B with rightwards arrow on top space straight x space straight A with rightwards arrow on top then the angle between A and B isπ
  • π

  • π/3

  • π/2

  • π/2

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5.

A projectile can have the same range R for two angles of projection. If T1 and T2 be the time of flights in the two cases, then the product of the two time of flights is directly proportional to

  • 1/R2

  • 1/R

  • R

  • R

271 Views

6.

Which of the following statements is false for a particle moving in a circle with a constant angular speed?

  • The velocity vector is tangent to the circle.

  • The acceleration vector is tangent to the circle.

  • The acceleration vector points to the centre of the circle.

  • The acceleration vector points to the centre of the circle.

165 Views

7.

An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 cm. If the car is going twice as fast, i.e 120 km/h, the stopping distance will be

  • 20 m

  • 40 m

  • 60 m

  • 60 m

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8.

A machine gun fires a bullet of mass 40 g with a velocity 1200 ms−1. The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most?

  • one 

  • Four

  • Two

  • Two

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9.

Two masses m1 = 5 kg and m2 = 4.8 kg tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when lift free to move?
(g = 9.8 m/s2 )

  • 0.2 m/s2

  • 9.8 m/s2

  • 5 m/s2

  • 5 m/s2


A.

0.2 m/s2


On release, the motion of the system will be according to the figure.
m1g - T = m1a ...... (i)  and
T - m2g = m2a ...... (ii)

On solving;

straight a space equals space open parentheses fraction numerator straight m subscript 1 minus straight m subscript 2 over denominator straight m subscript 1 plus straight m subscript 2 end fraction close parentheses space straight g space........ space left parenthesis iii right parenthesis

Here, m1 = 5 kg, m2 = 4.8 kg, g = 9.8 m/s2

straight a space equals space open parentheses fraction numerator 5 minus 4.8 over denominator 5 plus 4.8 end fraction close parentheses space straight x space 9.8
space equals space fraction numerator 0.2 over denominator 9.8 end fraction space straight x space 9.8
space equals space 0.2 space straight m divided by straight s squared

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10.

A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?

  • 7.2 J

  • 3.6 J

  • 120 J

  • 120 J

266 Views

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