Question

Mass of a bucket full of water is 15 kg it is being pulled up from a 15 metre deep well due to the hole in the bucket 6 kg water flows out of the bucket the work done in drawing the bucket out of the well will be

Answer 1

mass = 15 kg
loss in mass= 6kg
total mass= 15-6 = 9 kg
acceleration due to gravity= g= 9.8 
distance = s = 15m

work done = w = F x s
w = m x a x s
= 9 x 9.8 x 15
= 1323.0 J 

Answer 2

Explanation:

mass varies from deep of well to 15 m in height .

let ¢ is mass per unit height . 

so, 

dm  = ¢dx 

       =  6/15dx 

M =  m-dm

now,

workdone = change in potential energy 

= F× x

= ( m -dm)g ×  x

= mgx -dm×gx 

= 15 × 10 × 15 -6/15 gx.dx

=2250 - 6/15 x10x 225/2 

=2250 -  3 x 15x 10

= 2250 - 450

= 1800 Joule

============================================================