Reconsider the previous example if the sphere is made of stainless steel and is placed in a room (T a = 20 ◦C) in where the air is only gently mixed. The heat transfer coefficient between the sphere...

Reconsider the previous example if the sphere is made of stainless steel and is placed in a room (T_a
= 20 ◦C) in where the air is only gently mixed. The heat transfer coefficient between the sphere and the surroundings is found to be h = 50 W/m²
K. What is the rate at which the sphere’s center temperature changes?