Question

Two metal spheres of same material have diameter in the ratio of 1 is to 2 the ratio of their rates of cooling is

Answer 1

Answer:

1/8.

Explanation:

Since, we know that the rate of cooling is having a formulae of rate of cooling=dT/dt of the sphere which will be equal to -mass*specific heat capacity*dQ/dt.

We know that the mass is volume * density or the mass will be density*4/2πr^3. Since, the densities are same and the heat capacities are also same. Therefore, the ratio of the rate of cooling will be (r1/r2)^3 which on solving we will get 1/8.

Answer 2

Answer:

  Radiation is directly proportinal to area of the surface so cooling  rate also will be dirctly proportional to the surface area hence ratio of cooling rate of these =r12r22=14=1:4

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