Same chapter3 marksDifficulty: Medium
A boy of mass 40 kg climbs a staircase of 20 steps, each 15 cm high, in 10 s. Calculate the power he develops. Take g = 10 m s−2.
Work, Energy and Power
3 marksDifficulty: Medium
State the principle of conservation of energy and give one example of its application.
Original Khojo Papers practice question — not from a past board paper.
Answer
Energy can neither be created nor destroyed; it can only be changed from one form into another, and the total energy of an isolated system remains constant. A body falling freely converts potential energy into kinetic energy, and the sum of the two stays the same throughout the fall.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
Where friction acts, the apparent loss appears as heat and sound, so the total is still conserved.
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