Thermal Properties of Matter Test

Result

Thermal Properties of Matter Test - 73

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Question 1
4 / -1

According to Newton\'s Law of cooling\', the rate of cooling of the body is proportional to the

A
Temperature of the body

B
Temperature of the surrounding

C
Fourth power of the temperature of the body

D
Difference of the temperature of the body and the surrounding
Question 2
4 / -1

According to Newton\'s law of cooling, the rate of cooling of a body is proportional to (Δθ)ⁿ, where Δθ is the difference of the temperature of he body and the surrounding, and n is equal to

A
One

B
Two

C
Three

D
Four

Solution
Question 3
4 / -1

A calorimeter of mass 0.2 kg and specific heat 900 J/kg–K. Containing 0.5 kg of a liquid of specific heat 2400 J/kg–K. Its temperature falls from 60^oC to 55^oC in one minute. The rate of cooling is

A
5 J/s

B
15 J/s

C
100 J/s

D
115 J/s

Solution
Question 4
4 / -1

A hot body at temperature T losses heat to the surrounding temperature T_s by radiation. If the difference in the temperature is small then, the rate of loss of heat by the hot body is proportional to

A

B

C

D
Question 5
4 / -1

Two rods (one semi-circular and other straight) of same material and of same cross-sectional area are joined as shown in the figure. The points A and B are maintained at different temperature. The ratio of the heat transferred through a cross-section of a semi-circular rod to the heat transferred through a cross-section of the straight rod in a given time is

A
2 : π

B
1 : 2

C
π : 2

D
3 : 2

Solution
Question 6
4 / -1

A cylinder of radius R made of a material of thermal conductivity K₁ is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity K₂. The two ends of he combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is

A

B

C

D

Solution
Question 7
4 / -1

Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at 0^oC and 90^oC respectively. The temperature of the junction of the three rods will be

A
45^oC

B
60^oC

C
30^oC

D
20^oC

Solution
Question 8
4 / -1

A room is maintained at 20^oC by a heater of resistance 20 ohm connected to 200 volt mains. The temperature is uniform through out the room and heat is transmitted through a glass window of area 1 m² and thickness 0.2 cm. What will be the temperature outside? Given that thermal conductivity K for glass is 0.2 cal/m/^oC/sec and J = 4.2 J/cal

A
15.24^oC

B
15.00^oC

C
24.15^oC

D
None of thse

Solution
Question 9
4 / -1

There is formation of layer of snow x cm thick on water, when the temperature of air is –θ^oC (less than freezing point). The thickness of layer increases from x to y in the time t, then the value of t is given by

A

B

C

D

Solution
Question 10
4 / -1

A composite metal bar of uniform section is made up of length 25 cm of copper, 1 cm of nickel and 15 cm of aluminium. Each part being in perfect thermal contact with the adjoining part. The copper end of the composite rod is maintained at 100^oC and the aluminium end at 0^oC. The whole rod is covered with belt so that no heat loss occurs at the sides. If K_Cu = 2K_Al and K_Al = 3K_Ni, the n what will be the temperatures of Cu-Ni and Ni-Al junction respectively

A
23.33^oC and 78.8^oC

B
83.33^oC and 20^oC

C
50^oC and 30^oC

D
30^oC and 50^oC

Solution