Question

A students performs cooling experiment with a solid sphere and hollow sphere of same material and size which are heated to the same temperature. If the temperature difference between each sphere and surroundings is around 30⁰C , then -

• A. The hollow sphere will cool at a faster rate
• B. The solid sphere will cool at a faster rate
• C. Both spheres will cool at the same rate
• D. Both spheres will cool at the same rate if temp. difference more than 30⁰C

Answer 1

Answer: (A)

The hollow sphere will cool at a faster rate

Answer 2

Rate of cooling $\frac{d\theta}{dt}$ µ $\frac{dQ}{ms}$

dQ is same so $\frac{d\theta}{dt}$ µ $\frac{1}{m}$

m_solid > m_hollow

hence hollow sphere will cool fast.