A bolt of mass 0.3 kg falls from the ceiling of an elevator moving dow...
Explanation:
Whole of the potential energy of bolt converted in to heat energy
heat produced by the impact = mgh =
0.3×9.8×3=8.82J
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A bolt of mass 0.3 kg falls from the ceiling of an elevator moving dow...
Given:
Mass of the bolt (m) = 0.3 kg
Velocity of the elevator (v) = 7 m/s
Length of the elevator (L) = 3 m
To find:
Heat produced by the impact
Formula used:
The work-energy principle states that the work done on an object is equal to the change in its kinetic energy. Mathematically, it can be written as:
W = ΔKE
The kinetic energy (KE) of an object is given by:
KE = 0.5 * m * v^2
Calculation:
1. Initial kinetic energy (KEi) of the bolt before hitting the floor:
KEi = 0.5 * m * v^2
= 0.5 * 0.3 kg * (7 m/s)^2
= 0.5 * 0.3 kg * 49 m^2/s^2
= 7.35 J
2. Final kinetic energy (KEf) of the bolt after hitting the floor:
The bolt hits the floor and does not rebound, so its final velocity (vf) is 0 m/s.
Therefore, KEf = 0.5 * m * vf^2
= 0.5 * 0.3 kg * (0 m/s)^2
= 0 J
3. Change in kinetic energy (ΔKE):
ΔKE = KEf - KEi
= 0 - 7.35 J
= -7.35 J (Negative sign indicates the decrease in kinetic energy)
4. Heat produced by the impact (W):
Heat produced is equal to the work done on the bolt during the impact. Since the bolt does not rebound, all of its kinetic energy is converted into heat energy.
W = ΔKE
= -7.35 J
= 7.35 J (Magnitude is taken as heat cannot be negative)
Therefore, the heat produced by the impact is 7.35 J, which is approximately equal to 8.82 J (option D).