Question

A cubical vessel of height 1 m is full of water. What is the amount of work done in pumping water out of the vessel? $(Take g = 10 ms^{-2})$

• A. 1250 J
• B. 5000 J
• C. 1000 J
• D. 2500 J

Answer 1

Answer: (B)

5000 J

Answer 2

The volume of water contained in the vessel would be equal to $V = l^3 = (1 m)^3 =lm^3$ Assuming water to be pure so the density of water would be equal to $d = 1000kg/m^3,$ hence the mass of water contained in the vessel would be equal to m = Vd = 1000 kg. Thus, the work done would be equal to $W =mgh =1000\times\frac{1}{2}=5000 J$