Question

Water falls from a height $500\, m$. What is the raise in temperature of water at bottom. If the whole energy remains in the water?
(Specific heat of water $4200 \,J / kg ^{\circ} C$ ):

• A. $ 0.19^{\circ} C$
• B. $ 2.3^{\circ} C$
• C. $ 0.59^{\circ} C$
• D. $ 1.17^{\circ} C$

Answer 1

Answer: (D)

Here: $h=500 \,mg =9.8\, m / s ^{2}$
$c=4200\, J / kg ^{\circ} C$
Using the relation $m g h=m c \Delta \theta$
$m \times 9.8 \times 500=m \times 4200 \times \Delta \theta$
So, $\Delta \theta=\frac{9.8 \times 500}{4200}$
$=1.17^{\circ} C$