Engineering :: Heat Transfer

@ : Home > Mechanical Engineering > Heat Transfer

41.

The rate of heat loss through a furnace wall is 1000 kcal per hour when inside temperature is 1000?C and outside wall temperature is 500?C. What should be the wall thickness in case the thermal conductivity of wall material is 0.5 kcal/m-hr?C

A.	12.5 cm	B.	25 cm
C.	40 cm	D.	50 cm
E.	60 cm

42.

In which of the following will the evaporation rate be large?

A.	Salt pan near the sea	B.	Narrow river surrounded by trees
C.	Covered swimming pool	D.	Near the mountain
E.	Leaking water from pipe.

43.

A fur coat on an animal will help the animal to be

A.	Warm in summer	B.	Cool in summer
C.	Warm in winter	D.	Cool in winter
E.	Safe in rains

44.

The density of water is maximum at

A.	20?C	B.	4?C
C.	0?C	D.	? 4?C
E.	Absolute zero

45.

In the temperature of air above a pond is 8?C thermal conductivity of ice is 0.005 C.G.S. units, latent heat of fusion of ice is 79.9 cal/gram the density of ice is 1 gm/cu.m, the time taken for the formation of ice layer of 1 cm thickness is

A.	200 seconds	B.	100 seconds
C.	12.5 seconds	D.	10 seconds
E.	None of the above

46.

The ratio of specific heats of a gas is 1.4 and the value of specific heat at constant pressure is 7.0 cal/mole ?C. The difference between specific heat at constant presure and specific heat at constant volume will be

A.	1.4	B.	1.7
C.	1/1.4	D.	2
E.	5

47.

If thermal conductivity of a material of wall varies as ko (1 - ?t ). The temperature at the centre of the wall will be

A.	Same as in case of constant thermal conductivity	B.	More than that in case of constant thermal conductivity
C.	Less than that in case of constant thermal conductivity	D.	Depends on other factors
E.	None of the above

48.

A body cools from 80?C to 70?C in 10 minutes. The time taken by the body for further cooling to 60?C will be

A.	5 minutes	B.	7 minutes
C.	10 minutes	D.	Less than 10 minutes
E.	More than 10 minutes

49.

A thermistor is a

A.	Thermo-couple	B.	Thermometer
C.	Thermal resistance	D.	Thermal insulation
E.	Miniature resistance

50.

The quantity of heat required to change the temperature of 1 gm of ice from -6?C to -5?C is known as

A.	Latent heat of freezing	B.	Specific heat
C.	Heat of vaporization	D.	Cold heat
E.	Freezing heat