Question

Four containers are filled with cool water and are placed in front of a radiative heater and allowed to warm. Heat losses due to conduction through the bottom and due to natural or forced convection are negligible. Which container warms the fastes?

A. shiny metal
B. dull metal
C. dull black
D. shiny black
E. they all warm up at the same rate

Answer 1

A dull black container warms up the fastest in front of a radiative heater due to its high emissivity, while a shiny metal container warms up the slowest because of its reflective properties.

Step-by-step explanation:

The question pertains to the warming up of water in containers made of different materials when placed in front of a radiative heater. When considering radiative heat transfer, surface emissivity plays a crucial role in determining how quickly an object absorbs heat. A dull black container would warm up the fastest due to its high emissivity, as black surfaces are more effective at absorbing heat than reflective ones. On the other hand, a shiny metal container has a low emissivity and reflects most of the radiation, thus it warms up the slowest. The dull metal and shiny black will warm up at rates between the dull black and shiny metal, but still slower than the dull black due to their respective surface properties.