Question

Why is water used to cool radiators of engines?

• A. It has a low density.
• B. It is easily available
• C. It is cheap
• D. It has high specific heat capacity.

Answer 1

The correct option is D It has high specific heat capacity.

From definition of specific heat capactiy,
$s=\frac{Q}{m\Delta T}$
For same mass and heat transferred,
$s\propto \frac{1}{\Delta T}$

Water has a very high specific heat capacity of about $4.2J{K}^{-1}g-1$. This means that for the same heat to be absorbed, the change in temperature of water will be lower.

In other words, we can also say that water can absorb large amount of heat for small temperature change making it suitable as a coolant.