Question

Water level in a well was 20m below ground level. During rainy season, rain water collected in different water tanks was drained nto the well and the water level rises 5 m above the previous level. The wall of the well is 1m 20 cm high and a pulley is fixed at a height of 80 cm. Raghu wants to draw water from the well. The minimum length of the rope that he can use is
(a) 17 m (b) 18 m (c) 96 m (d) 97 m

Answer 1

After water level rises 5 m above the previous level, water level is now (20 - 5) = 15 m below the ground level.
Height of the pulley from the ground level = 1 m 20 cm + 80 cm
                                                                   = 1.2 m + 0.8 m
                                                                   = 2 m
Therefore, the minimum length of the rope = 15 m + 2 m
                                                                    = 17 m.
Ans. (a) 17 m