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 $0.5\, kgm ^{-1}$. The work done in lifting water to the ground from the surface of water in the well $20\, m$ below is $\left(g=10\, ms ^{-2}\right)$

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

Answer 1

Answer: (A)

Work done in lifting water and drum $=60 \times 10 \times 20 \,J$
$=12000 \,J$
Total mass of ropes $=4 \times 0.5 \, kg =20 \,kg$
Work done in the case of ropes
$=20 \times 10 \times 10=2000 \, J$
Total work done $=14000 \, J$