select the ones that correspond to a system in thermal equilibrium a) A metal ro
ID: 1511720 • Letter: S
Question
select the ones that correspond to a system in thermal equilibrium
a) A metal rod sits on a table in a room at constant temperature. It has been there for half an hour.
b) A metal rod is inside a pan with boiling water. It has been there for half an hour.
c) The metal rod from option B is removed from the water and is placed on the table.
d) The metal rod from option B is removed from the water. Half of it is inserted in a block of Styrofoam (an excellent thermal insulator). The other half is surrounded by air.
e)A metal rod is partially submered in boiling water. The top half protrudes from the water and is surrounded by the air in the room. The rod has been there for half and hour.
Explanation / Answer
A system is in thermal equilibrium if heat transfer doesn't take place.
a.) In half an hour, the metal rod would have reached the room temperature and hence no heat transfer. So, in thermal Equilibrium.
b.) The rod, after being placed in the boiling water for half an hour would have reached the boiling temperature of the water (100 Celcius) and hence no temperature difference between water and the rod. So, no heat transfer. Hence in thermal equilibrium.
c.) The rod is hotter than the room temperature and hence heat transfers from the hot rod to the surroundings (room air). So, not in thermal equilibrium.
d.) There is a temperature difference between the exposed half of the hot rod and the surrounding air. So, heat transfer takes place and hence not in thermal equilibrium.
e.) There is a temperature difference between the exposed half of the rod and the room air. So, heat gets transferred from the upper half of the rod to the air and the temperature of the surrounding air increases. However, the entire room air would not have reached 100 Celcius in half an hour. So, the temperature difference is still there and heat transfer takes place and hence not in thermal equilibrium.
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