Answer to Question #91154 in Molecular Physics | Thermodynamics for Samiksha Pawar

Question

Arya's mother had a different concept of boiling rajma. She first boiled rajma with cold water. Then after two whistles in cooker she added normal water in appropriate amount. This method of boiling also saved time.
a). Why did arya's mother add cold water to rajma??
b). What type of heat energy is required for this??
C). How this energy helped in faster cooking?

Answer 1

a). Why did arya's mother add cold water to rajma??

The cold water generally gains heat more rapidly than water that is already hot.

b). What type of heat energy is required for this??

In this case, convection describes heat transfer.

C). How this energy helped in faster cooking?

The relationship for heat transfer by convection is given by Fourier's law:

$$\frac { dQ} {dt}=-hAΔT(t)$$

where Q is the thermal energy, h is the heat transfer coefficient, A is the heat transfer surface area, ΔT(t) is the time-dependent thermal gradient between environment and object