Rita and Sameer each lift identical school bags of mass 15kg from the ground to the same shelf 1.5m high. Rita completes the task in 2s, while Sameer takes 3s. A third student, Karan, lifts a lighter bag of mass 10kg to the same shelf in 1.5s. Use this information to answer the following parts.
a. (i) Explain what is meant by the power developed by a person in this situation.
b. (ii) Without performing any numerical calculation, arrange Rita, Sameer and Karan in the order of decreasing power and justify your answer qualitatively.
c. (iii) If the height of the shelf were doubled for all three students while their times remained unchanged, would your answer to part (ii) change? Give reasons for your choice.