Tag: physics

Questions Related to physics

Two bodies are in thermal equilibrium if they have same

  1. temperature

  2. amount of heat

  3. specific heat

  4. thermal capacity


Correct Option: A
Explanation:

Thermal equilibrium means that there is no heat transfer going on between the bodies, which simply means that the bodies are at the same temperature. Heat content is a whole different concept - it is the amount of heat contained in a body, which is crucially dependent on mass. 

Two bodies A and B are said to be in thermal equilibrium with each other, if

  1. heat flows from A to B

  2. heat flows from B to A

  3. both the bodies lose equal amunts of heat to the atmosphere

  4. heat does not flow from either A or B


Correct Option: D
Explanation:

Two bodies A and B are said to be in thermal equilibrium with each other, ifheat does not flow from either A or B 

Two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other.
The above statement is

  1. First law of thermodynamics

  2. Second law of thermodynamics

  3. Third law of thermodynamics

  4. Zeroth law of thermodynamics


Correct Option: D
Explanation:

The given statement is the exact statement of Zeroth law of thermodynamics which deals with thermal equilibrium.

Three bodies $A, B$ and $C$ are in thermal equilibrium.
The temperature of $B$ is $45^{\circ}C$. Then the temperature of $'C'$ is _____

  1. $45^{\circ}C$

  2. $50^{\circ}C$

  3. $40^{\circ}C$

  4. Any temperature


Correct Option: A
Explanation:

A, B and C are in thermal equilibrium and B is at temperature $45^0 C$, then according to zeroth law of thermodynamics both A and C will also be at temperature $45^0 C$.

If the output energy is$ 1000 J$ and input energy is $200 J $the net output is _____ $J$.

  1. $800$

  2. $1200$

  3. $10$

  4. $500$


Correct Option: A
Explanation:

The net output $=$ output - input
$= 1000 - 200 = 800 J$

In thermal equilibrium concepts, heat lost by hot body is equal to

  1. Heat gained by hot body

  2. Heat gained by cold body

  3. Both (a) and (b)

  4. None of these


Correct Option: B
Explanation:

It is very clear that heat flows from hot body to cold body under general conditions. 

So (B) is the correct option. 

The variance defined by Zeroth law of thermodynamics is

  1. Temperature

  2. Internal energy

  3. Work

  4. All of these


Correct Option: A

Four cubes of ice at $-10^{o}C$ each one gm is taken out from the refrigerator and are put in $150\ gm$ of water at $20^{o} C$. The temperature of water when thermal equilibrium is attained. Assume that no heat is lost to the outside and water equivalent of container is $46\ gm$. (Specific heat capacity of water $=1\ cal/gm-\ ^{o}C$, Specific heat capacity of fusion of ice $=0.5 cal/gm-\ ^{o}C$, Latent heat of fusion of ice $= 80\ cal/gm$)

  1. $0^{o}C$

  2. $-10^{o}C$

  3. $17.9^{o}C$

  4. $None$


Correct Option: A

$1\ g$ of ice is mixed with $1\ g$ of steam. At thermal equilibrium, the temperature of the mixture is

  1. $50^{\circ}C$

  2. $0^{\circ}C$

  3. $55^{\circ}C$

  4. $100^{\circ}C$


Correct Option: D

Two bodies are said to be in the state of thermal equilibrium if there is no transfer of heat taking place between them. True or false.

  1. True

  2. False


Correct Option: A
Explanation:
Thermal equilibrium is said to be achieved when there is no exchange of heat in the system.
Hence, OPTION : A (true).