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Grade 12Mechanics

  1. A man weighing 6o kg lifts a body of 15kg to the top a building 10m high in 3 minutes.What is his efficiency?
  2. A body of mass m is moving in acircle of radius R with a constant speed v.The force on the body is mv^2/R and isdirected towards the centre.What is the work done by the force in moving the body half the circumference of the circle?
  3. A metal ring of mass 2.1 kg and of 10cm radius is revolving about its axis making 100/pi rev/s..If this ring is dropped in a viscous liquid the heat generated in the liqiud is equal to ??? (given J=4.2 joule/cal)
  4. A cyclist turn around a curve at 40km/hr.If it runs the curve at double the speed its tendency to overturn is ???

Profile image of upasana bhuyan
13 Years agoGrade 12
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1 Answer

Profile image of Prajwal kr
13 Years ago

1. Workdone= 1500 J

    Workdone by time gives efficiency: 8.333 W

2. 0. as F and displacement are perpendicular to each other.

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