NCERT Solutions for Chapter: Heat, Exercise 3: SHORT ANSWER QUESTIONS

For setting curd, a small amount of curd is added to warm milk. The microbes present in the curd help in setting if the temperature of the mixture remains approximately between $35°\mathrm{C}$ to $40°\mathrm{C}$. At places, where room temperature remains much below the range, the setting of curd becomes difficult. Suggest a way to set curd in such a situation.

You may have noticed that a few sharp jerks are given to the clinical thermometer before using it. Why is it done so?

Why is it advised not to hold the thermometer by its bulb while reading it?

At a campsite there are tents of two shades - one made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give reasons for your choice. Would you like to prefer the same tent during winter?

While constructing a house in a coastal area, in which direction should the windows preferably face and why?

Observe the picture given below. Water is being boiled in a pan of wide base.

Which position $P$ or $T$ will feel warmer?

Observe the picture given below. Water is being boiled in a pan of wide base.

Fill up the boxes $P$ and $T$ to indicate the mode of flow of heat to the hand.

Look at figure given below.

The length of wire $PQ$ in case of $A$ is equal to the diameter of the semicircle formed by the wire $CDE$, in case $B$. One pin is attached to each wire with the help of wax as shown in the figure. Which pin will fall first? Explain.