cooling rate of a sphere of 600 K at external environment (200 K) is R. When the temperature of sphere is reduced to 400 K then cooling rate of the sphere becomes : (1) 3/16 R (2) 16/3 R (3) 9/27 R (4) None

Q. A sphere at temperature 600 K is placed in environment of temperature 200 K, its cooling rate is H. If the temperature is reduced to 400 K, the cooling is same environment will be :

Q. Assertion :A solid sphere and a hollow sphere of same material and same radius are kept at same temperatures in atmosphere. Rate of cooling of hollow sphere will be more. Reason: If all other conditions are same, then rate of cooling is inversely proportional to mass of body.

Q. Four spheres $A,B,C$ and $D$ of different metals but of same radius are kept at same temperature. The ratio of their densities is $2:3:5:1$. If specific heats of their materials are in the ratio $3:6:2:4$, which sphere will show initially the fastest rate of cooling?

Q. Four spheres $A,B,C$ and $D$ of different metals but of same radius are kept at same temperature.The ratios of their densities and specific heats are $2:3:5:1$ and $3:6:2:4.$ Which sphere will show the fastest rate of cooling (initially)?

Q. A hot metallic sphere of radius $r$ radiates heat. It's rate of cooling is