AP EAMCET2006PhysicsThermal Properties of Matter
Two solid spheres A and B made of the same material have radii r_A and r_B respectively. Both the spheres are cooled from the same temperature under the conditions valid for Newton's law of cooling. The ratio of the rate of change of temperature of A and B is :
Options
- Ar_A r_B
- Br_B r_A
- Cr_A^2 r_B^2
- Dr_B^2 r_A^2
Correct answer
B. r_B r_A
Step-by-step solution
4 3 r^3 c (- d T d t )= 4 r^2 (T^4-T₀^4 ) (- d T d t )= 3 r c (T^4-T₀^4 )=H (say) Ratio of rates of fall of temperature H_A H_B = r_B r_A