A box is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to | Motion in Straight Line

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 Multiple Choice QuestionsMultiple Choice Questions

111.

A rocket of mass 100 kg burns 0.1 kg of fuel per sec. If velocity of exhaust gas is 1 km/sec, then it lifts with an acceleration of

  • 1000 ms-2

  • 100 ms-2

  • 10 ms-2

  • 1 ms-2


112.

A bullet emerge from a barrel of length 1.2 m with a speed of 640 ms-1 . Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is

  • 4 ms

  • 40 ms

  • 400 μs

  • 1 s


113.

The acceleration a (in ms-2 ) of a body, starting from rest varies with time t (in s) following the equation a = 3 t + 4. The velocity of the body at time t = 2 s will be

  • 10 ms-1

  • 18 ms-1

  • 14 ms-1

  • 26 ms-1


114.

Figure below shows the distance-time graph of the motion of a car. It follows from the graph that the car is

  • at rest

  • in uniform motion

  • in non-uniform acceleration

  • uniformly accelerated


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 Multiple Choice QuestionsShort Answer Type

115.

A shell of mass m is at rest initially. It explodes into three fragments having masses in the ratio 2 : 2 : 1. The fragments having equal masses fly off along mutually perpendicular direction with speed v. What will be the speed of the third (lighter) fragment ?


 Multiple Choice QuestionsMultiple Choice Questions

116.

If a person can throw a stone to maximum height of h metre vertically, then the maximum distance through which it can be thrown horizontally by the same person is

  • h2

  • h

  • 2h

  • 3h


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117.

A box is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to

  • t1/2

  • t3/4

  • t3/2

  • t2


C.

t3/2

We are given that a box is moved along a straight line by a machine under constant power. So, we have power

                          P = Fv = mav           P = mdvdt vor vdv = Pm dt        v22 = Ptmor        v = 2Pm tor     dxdt = 2Pm t      dx = 2Pm t1/2dt           x = 2Pm t1/2dt           x = 2Pm t3/23/2        x  t3/2


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118.

A particle is moving with a constant speed v in a circle. What is the magnitude of average velocity after half  rotation ?

  • 2v

  • 2vπ

  • v2

  • v2π


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119.

A box of mass 2 kg is placed on the roof of a car. The box would remain stationary until the car attains a maximum acceleration. Coefficient of static friction between the box and the roof of the car is 0.2 and g = 10 ms-2. This maximum acceleration of the car, for the box to remain stationary, is

  • 8 ms-2

  • 6 ms-2

  • 4 ms-2

  • 2 ms-2


120.

A particle is travelling along a straight line OX. The distance x (in metre) of the particle from O at a time t is given by x = 37 + 27t − t3, where t is time in seconds. The distance of the particle from O when it comes to rest is

  • 81 m

  • 91 m

  • 101 m

  • 111 m


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