Question

$\huge{\mathcal{\underline{\green{Question}}}}$
A bolt of mass 0.3 kg falls from the ceiling of an elevator moving down with an uniform speed of 7m/s. 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 ?​

Answer 1

Thus the exact final velocity of the bolt is also 7 m/s. So, the velocity of the bolt during the fall is uniform. This implies that there is no change in the kinetic energy of the bolt i.e., ΔK=0 . Substituting the values for m=0.3kg , g=9.8m/s2 and h=3m in the above equation we get, U=0.3×9.8×3=8.82J

Answer 2

Answer:

Mass of Bolt = m = 0.3kg

Speed of Elevator = 7m/s

height ( length of Elevator ) = 3m

hair the relativity velocity of bolt w.r.t. the elevator is zero potential energy will be converted to heat energy with the loss of energy , So

Loss in potential energy = heat produced

= mgh = 0.3 × 9.8 × 3

≈ 8.82J