Question 824: Thermodynamics & KTG

Question

A sphere, a cube and a thin circular plate all made of same material and having the same mass are heated to same temperature of $$200^{\circ} \mathrm{C}$$. When these are left in a room.

Accepted Answer

$$ho=\frac{M}{V}$$;
Given: three objects are of same materials $$ho$$ is same. Also, $$\mathrm{M}=$$ same,
$$	herefore \quad$$ volume of objects is same.
For constant volume, amongst the given objects surface area of the plate is maximum.
Hence according to Stefan's law $$\frac{\mathrm{dQ}}{\mathrm{dt}} \propto \mathrm{AT}^4$$
As $$A_{	ext {plate }}$$ is maximum, the plate will cool fastest and reaches room temperature fast.

Answer

the sphere reaches room temperature fast

Answer

the cube reaches room temperature fast

Answer

the circular plate reaches room temperature fast

Answer

all will reach the room temperature simultaneously

Thermodynamics & KTG

A sphere, a cube and a thin circular plate all made of same material and having the same mass are heated to same temperature of $200^{\circ} \mathrm{C}$. When these are left in a room.

Choose the correct answer: