Compare the rate of heat transfer by radiation for two objects, the first one has the temperature Ts1= 25 degree Celsius and the second is kept at temperature Ts2 = 40 degree Celsius. Suppose they are made of identical material (e1=e2) and have the same area participating in radiation (Ar1=Ar2). The Surrounding temperature Tr= 25 degree Celsius.

The rate of heat transfer of the second object is greater than the first object.

Explanation:

= Emissivity of the object

= Stefan-Boltzmann constant =

= Temperature of surface 1 =

= Temperature of surface 2 =

= Surrounding temperature =

Rate of heat transfer is given by

So,

Hence, the rate of heat transfer of the second object is greater than the first object.

the average speed is 24.57 km/hr

object 2 because all the other ones are wrong