Question

Question 6.27 A bolt of mass 0.3 kg falls from the ceiling of an elevator moving down with an uniform speed of 7 m s–1. It hits the floor of the elevator (length of the elevator = 3 m) and does not rebound. What is the heat produced by the impact? Would your answer be different if the elevator were stationary?

Chapter Work, Energy And Power Page 138

Answer 1

Hey there !!!!!

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By using law of conservation of energy heat produced by the impact will be equal to loss in potential energy.

H = mgh

m = 0.3kg g=9.8m/s² h=3m

Heat produced = 0.3*9.8*3 = 8.82 J

Heat produced is the same for all cases as in each and every case relative velocity of bolt is zero.

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Hope this helped you............................


 

Answer 2

Mass of bolt = m = 0.3 kg 
speed of elevator = 7m/s
height(length of elevator)  = h = 3m 

here the relative velocity of bolt w.r.t the elevator is zero 
so potential energy will be converted to heat energy with the loss of energy,

so 
loss in p.E = heat produced 
= mgh = 0.3 ×9.8×3 
=> 8.82 jule