Question

The mass of a bucket containing water is 10 kg. What is the work done in pulling up the bucket from a well of depth 10 m if water is pouring out at a uniform rate from a hole in it and there is loss of 2kg of water from it while it reaches the top $(g=10m/se{c}^2)$

• A. 1000 J
• B. 800 J
• C. 900 J
• D. 500 J

Answer 1

The correct option is C

900 J

Gravitational force on bucket at starting position $=mg=10\times 10=100N$

Gravitational force on bucket at final position $=8\times 10=80N$

So the average force through out the vertical motion $=\frac{100+80}{2}=90N$

$\therefore$ Work done $=Force\times displacement=90\times 10=900J$