Q12 of 27 Page 79

A glass full of hot milk is poured on the table. It begins to cool gradually. Which of the following is correct?

Lost of heat is directly proportional to the temperature difference with surrounding and body. So as milk cool, temperature difference decreases so rate of cooling decreases with time so from here we can say option (a) is wrong.

According to Newton’s law of cooling the heat of milk falls exponentially so option (b) is correct.


While cooling very small amount of heat also flows from surrounding to milk as compared to heat lost by milk to surrounding so option (c) is also correct.


By conduction, convection and radiation, when hot milk spread on table it transfer heat to surroundings. Hence option (d) is correct.

More from this chapter

All 27 →
10

‘Gulab Jamuns’ (assumed to be spherical) are to be heated in an oven. They are available in two sizes, one twice bigger (in radius) than the other. Pizzas (assumed to be discs) are also to be heated in oven. They are also in two sizes, one twice big (in radius) than the other. All four are put together to be heated to oven temperature. Choose the correct option from the following:

 11

Refer to the plot of temperature versus time (Fig. 11.2) showing the changes in the state of ice on heating (not to scale).

Which of the following is correct?


 13

Is the bulb of a thermometer made of diathermic or adiabatic wall?

 14

A student records the initial length l, change in temperature ∆T and change in length ∆l of a rod as follows:


If the first observation is correct, what can you say about observations 2, 3 and 4.