A black body of surface area 10 ${\mathrm{cm}}^2$ is heated to 127°C and is suspended in a room at temperature 27°C. The initial rate of loss of heat from the body at the room temperature will be 

1. 2.99 W               

2. 1.89 W

3. 1.18 W               

4. 0.99 W

Two identical objects A and B are at temperatures ${\mathrm{T}}_{\mathrm{A}}$ and ${\mathrm{T}}_{\mathrm{B}}$ respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperatures T(${\mathrm{T}}_{\mathrm{A}}$>T>${\mathrm{T}}_{\mathrm{B}}$)The objects A and B attain temperature T eventually which one of the following is correct statement

1. ‘A’ only emits radiations while B only absorbs them until both attain temperature

2. A loses more radiations than it absorbs while B absorbs more radiations that it emits until temperature T is attained

3. Both A and B only absorb radiations until they attain temperature T

4. Both A and B only emit radiations until they attain temperature T

When the body has the same temperature as that of surroundings

1. It does not radiate heat

2. It radiates the same quantity of heat as it absorbs

3. It radiates less quantity of heat as it receives from surroundings

4. It radiates more quantity of heat as it receives heat from surroundings

The temperature of a liquid drops from 365 K to 361 K in 2 minutes. Find the time during which temperature of the liquid drops from 344 K to 342 K . Temperature of room is 293 K

1. 84 sec                       

2. 72 sec

3. 66 sec                       

4. 60 sec

Newton’s law of cooling, holds good only if the temperature difference between the body and the surroundings is

1. Less than 10$°\mathrm{C}$      

2. More than 10$°\mathrm{C}$

3. Less than 100$°\mathrm{C}$     

4. More than 100$°\mathrm{C}$

The temperature of a body falls from \(50^{\circ}\text{C}\)$\mathrm{}$ to \(40^{\circ}\text{C}\)$\mathrm{}$ in \(10\) minutes. If the temperature of the surroundings is \(20^{\circ}\text{C},\)$\mathrm{ t}$hen the temperature of the body after another \(10\) minutes will be:
1. \(36.6^{\circ}\text{C}\)          
2. \(33.3^{\circ}\text{C}\)$\mathrm{}$
3. \(35^{\circ}\text{C}\)             
4. \(30^{\circ}\text{C}\)$\mathrm{}$

A body takes 5 minutes to cool from 90$°\mathrm{C}$ to 60$°\mathrm{C}$. If the temperature of the surroundings is 20$°\mathrm{C}$, the time taken by it to cool from 60$°\mathrm{C}$ to 30$°\mathrm{C}$ will be. 

1. 5 min                   

2. 8 min

3. 11 min                 

4. 12 min

An object is cooled from 75°C to 65°C in 2 minutes in a room at 30°C. The time taken to cool another object from 55°C to 45°C in the same room in minutes is -

1. 4                   

2. 5

3. 6                   

4. 7

A cane is taken out from a refrigerator at 0°C. The atmospheric temperature is 25°C. If ${\mathrm{t}}_1$ is the time taken to heat from 0°C to 5°C and ${\mathrm{t}}_2$ is the time taken from 10°C to 15°C, then 

1. ${\mathrm{t}}_1>{\mathrm{t}}_2$                         

2. ${\mathrm{t}}_1<{\mathrm{t}}_2$

3. ${\mathrm{t}}_1={\mathrm{t}}_2$                        

4. There is no relation

Two rods (one semi-circular and the other straight) of the same material and of the same cross-sectional area are joined as shown in the figure. The points \(A\) and \(B\) are maintained at different temperatures. The ratio of the heat transferred through a cross-section of a semi-circular rod to the heat transferred through a cross-section of a straight rod at any given point in time will be:
                 
1. \(2:\pi\)
2. \(1:2\)
3. \(\pi:2\)
4. \(3:2\)