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Grade 12Mechanics

An apple gives 21 kilo joule energy to a boy how much height he can climb by using this energy if is efficiency is 28% mass of the boy is 40 kg

Profile image of Arti Bhagwan tijare
9 Years agoGrade 12
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1 Answer

Profile image of Ankit Jaiswal
9 Years ago
Hi Arti,
          as given in the question an apple gives 21 KJ of energy of which  the boy can use 28% to do any work (efficiency)
          so, the work done by boy is
          21x1000x28/100 = 21x280 =5880 J
         this energy is use up by the boy to climb the tree hence
 
         mgh = 5880 J
      \therefore 40x9.8 = 5880
      \therefore h = 5880/(40x9.8) m     (i have taken g is 9.8 for easy claculation you can take according to the question)
      \therefore h = 15 meters