A shpere, a cube and a disc all of the same material, quality and volume are heated to 900K and left in air. Which of these will have the lowest rate of cooling
A wall has two layers A and B, each made of a different material. Both the layers have the same thickness. The thermal conductivity of material of A is twice that of B. Under the thermal equilibrium the temperature difference across the wall is 30?C. The temperature drops in layers A and B will be respectively
Four balls made of lead, glass, brass and iron made of same size, are heated to 100?C. They are simultaneously placed on a sheet of paraffin nearly 5 mm thick. Which ball will drop first?
Four rods with different radii 'r' and length 'l' are used to connect to reservoirs of heat at different temperature. Which one of them with conduct most heat?
Two large closely spaced concentric spheres (both of which are perfect black body radiators) are maintained at temperatures of 127?C and 27?C respectively. The space in between the two spheres is evacuated. Taking Stefan Boltzmann constant as 5.67 x 108 watt m2K the rate of radiation in watts per sq. m between the two spheres is approximately
Four identical copper cubes are painted with different paints. Now if all the cubes are heated to the same temperature and are left in vacuum, which cube will lose heat more rapidly? The colours of the cubes are
