Physics-
General
Easy

Question

A loop of radius 3 meter and weighs 150 kg. It rolls along a horizontal floor so that its centre of mass has a speed of 15 cm/sec. How much work has to be done to stop it –

  1. 3.375 J  
  2. 7.375 J  
  3. 5.375 J  
  4. 9.375 J  

The correct answer is: 3.375 J


    Required work = Total K.E.
    = fraction numerator 1 over denominator 2 end fraction mv2 open parentheses 1 plus fraction numerator k to the power of 2 end exponent over denominator R to the power of 2 end exponent end fraction close parentheses
    = fraction numerator 1 over denominator 2 end fraction M v to the power of 2 end exponent open square brackets 1 plus fraction numerator k to the power of 2 end exponent over denominator R to the power of 2 end exponent end fraction close square brackets
    = fraction numerator 1 over denominator 2 end fraction× 150× (0.15)2 (1+ 1) = 3.375 J

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