Question

Water level in a well was 20 metres below the ground level. During rainy season, rain water collected in different water tanks was drained into a well and water level rises above the previous level. The wall of the well is 1 metre 20 cm high and a pulley is fixed at a height of 80 cm. Raghu wants to draw water from the well. What is the minimum length of the rope that he can use ? What value is depicted by Raghu in this question ?

Answer 1

$$\begin{gathered} \mathrm{Note}\mathrm{that}\mathrm{the}\mathrm{water}\mathrm{level}\mathrm{in}\mathrm{a}\mathrm{well}\mathrm{was}20\mathrm{meters}\mathrm{below}\mathrm{the}\mathrm{ground}\mathrm{level}. \\ \mathrm{The}\mathrm{wall}\mathrm{of}\mathrm{the}\mathrm{well}\mathrm{is}1\mathrm{meter}20\mathrm{cm}\mathrm{high}. \\ \mathrm{So}\mathrm{the}\mathrm{total}\mathrm{depth}\mathrm{of}\mathrm{the}\mathrm{water}\mathrm{level}\mathrm{from}\mathrm{the}\mathrm{top}\mathrm{of}\mathrm{the}\mathrm{wall}\mathrm{is}, \\ 20\mathrm{meters}+1\mathrm{meters}20\mathrm{cm}=21.20\mathrm{meters} \\ \mathrm{Also},\mathrm{the}\mathrm{pulley}\mathrm{is}\mathrm{fixed}\mathrm{at}\mathrm{a}\mathrm{height}\mathrm{of}80\mathrm{cm}\mathrm{that}\mathrm{is}0.80\mathrm{meter} \\ \mathrm{So}\mathrm{the}\mathrm{minimum}\mathrm{length}\mathrm{of}\mathrm{the}\mathrm{rope}\mathrm{which}\mathrm{he}\mathrm{can}\mathrm{use}\mathrm{is}, \\ 21.20+0.80\mathrm{meters}=\mathbf{22}\mathbf{}\mathbf{meters} \end{gathered}$$