The required energy depends on flag mass, gravitational acceleration and pole height. Raising it slowly or quickly does not change the work done. Doubling the lifting speed halves the time, doubling the required power.
Which factors determine the energy required to raise a flag from the ground to the top of a tall flagpole using a pulley? Does raising the flag slowly or quickly change the amount of work done? If the speed at which the flag is raised is doubled, how does the power requirement change? Explain your answers.
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The energy required is determined by the mass of the flag, acceleration due to gravity and vertical height of the flagpole. The work done equals m g h and remains independent of speed or time. However, doubling the speed cuts the time taken in half. Since power is work divided by time, halving the time doubles the power requirement.
For more NCERT Solutions of Class 9 Science Exploration Chapter 7 Work, Energy and Simple Machines Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-7/