Question

Water is drawn from a well in a 5 kg drum of capacity 55 L by two ropes connected to the top of the drum. The linear mass density of each rope is 0.5 kg$m^{-1}$. The work done in lifting water to the ground from the surface of water in the well 20 m below is [g = 10 m$s^{-2}$]

• A. $1.4\times {10}^{4}J$
• B. $1.5\times {10}^{4}J$
• C. $9.8\times {10}^{6}J$
• D. 18 J

Answer 1

The correct option is A

$1.4\times {10}^{4}J$

Work done in lifting water and drum is 60×10×20 J =12000 J
Total mass of ropes =40 $\times$ 0.5 kg =20 kg
Work done in the case of ropes is 20 $\times$ 10 $\times$ 10 = 2000 J

Total work done = 14000 J