"A solid sphere of copper of radius R and a hollow sphere of the same material of inner radius r and outer radius R are heated to the same temperature and allowed to cool in the same environment. Which of them starts cooling faster ?''

"A solid sphere of copper of radius R and a hollow sphere of the same

1.	"A solid sphere of copper of radius R and a hollow sphere of the same material of inner radius r and outer radius R are heated to the same temperature and allowed to cool in the same environment. Which of them starts cooling faster ?''
Answer» Solution :Rate of loss of HEAT = mass x SPECIFIC heat x rate of cooling. The surface AREA of HOLLOW and solid sphere are equal. But mass is LESS for hollow sphere. So rate of cooling of holow sphere is faster.