# Q27 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?

D Devendra Khairwa

In this case, the heat produced is the loss in the potential energy.

Thus,

heat produced  =  mg h

or                                            $=\ 0.3\times 9.8\times 3$

or                                            $=\ 8.82\ J$

The heat produced (when the lift is stationary) will remain the same as the relative velocity of the bolt with respect lift still remains zero.

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