On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision, the first block moves at an angle θ to its initial direction and has a speed v/3/ The second block's speed after the collision is 

  • 3/4 v


A.


According to law of conservation of kinetic energy, we have



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The heart of a man pumps 5 L of blood through  the arteries per minute at a pressure of 150 mm of mercury . If the density of mercury be 13.6 x 103 kg/ m3 and g = 10 m/s2, then the power of heart in watt is  

  • 1.70

  • 2.35

  • 3.0

  • 3.0


A.

1.70

 Given, pressure = 150 mm of Hg
Pumping rate of heart of a man

 = 

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Water falls from a height of 60 m at the rate of 15 kg /s to operate a turbine. The losses due to frictional 

  • 8.1 kW

  • 10.2 kW

  • 12.3 kW

  • 12.3 kW


A.

8.1 kW

Power generated by the turbine is,

Pgenerated = Pinput  x 90/100


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An engine pumps water through a hosepipe. Water passes through the pipe and leaves it with a velocity of 2 ms-1. The mass per unit length of water in the pipe is 100 kgm-1. What is the power of the engine?

  • 400 W

  • 200 W

  • 100 W

  • 100 W


D.

100 W

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A tube of length L is filled completely with an incompressible liquid of mass M and closed at both the ends. The tube is then rotated in a horizontal plane about one of its ends with a uniform angular velocity ω. The force exerted by the liquid at the other end is

  • MLω squared over 2
  • fraction numerator ML squared straight omega over denominator 2 end fraction
  • MLω squared
  • MLω squared

A.

MLω squared over 2

Let the length of a small element of tube be dx. 
Mass of this element
          


where M is mass of filled liquid and L is length of tube. 
Force on this element
      

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