Two closed vessels contain equal volumes of boiling water and are identical except that one is blackened on the outside while the other is polished. Which of the following is correct?
the polished vessel will cool faster because a polished surface is a good radiator
the polished vessel will cool faster because it will absorbe less heat from the room
the black vessel will cool faster because it is a better conductor of heat
the polished vesselwill cool faster because it reflects heat better
the black vessel will cool faster because a black surface radiates heat faster than a polished one
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The answer according to the textbook, THE SCIENCE PHYSICS is E, the black vessel will cool faster because it surface radiates heat faster than polished one. this is proven because black is a perfect radiator and absorber of heat
Here's the breakdown of why the correct answer is E:
Radiation: Hot objects lose heat through radiation. The rate at which an object radiates heat depends on its surface properties.
Black vs. Polished Surfaces:
Black surfaces are excellent absorbers and emitters (radiators) of thermal radiation. They absorb most of the radiant energy that falls on them and also radiate heat effectively.
Polished surfaces are poor absorbers and emitters of thermal radiation. They reflect most of the radiant energy that falls on them.
Analyzing the options:
A. the polished vessel will cool faster because a polished surface is a good radiator: This is incorrect. Polished surfaces are poor radiators.
B. the polished vessel will cool faster because it will absorb less heat from the room: While a polished surface absorbs less radiant heat from the surroundings, the primary mode of heat loss for the boiling water will be its own radiation. The difference in heat absorption from the room will likely be less significant than the difference in heat emission.
C. the black vessel will cool faster because it is a better conductor of heat: The material and thickness of the vessels (stated as identical) determine heat conduction, not just the surface color. While the black surface might absorb heat slightly better initially, the dominant factor in cooling will be heat loss to the surroundings.
D. the polished vessel will cool faster because it reflects heat better: While it reflects external heat, it also reflects its own internal heat radiation back in, hindering cooling.
E. the black vessel will cool faster because a black surface radiates heat faster than a polished one: This is correct. The boiling water in both vessels will lose heat primarily through radiation to the cooler surroundings. The black vessel, being a better radiator, will lose heat at a faster rate than the polished vessel.
Therefore, the black vessel will cool faster due to its higher emissivity (ability to radiate heat).
Final Answer: The final answer is
theblackvesselwillcoolfasterbecauseablacksurfaceradiatesheatfasterthanapolishedone
plz let d max number of questions b exact wit dat gvn by jamb wit corresponding time limit
the heat in the question under investigation is inside the two vessels not outside get the point!
polished vessel reflect heat,thereby it resist heat 4rm gettin into d vessel while black vessel radiate heat,so it is obvious dat d black vessel wil take longer time before it get cooled.
The correct answer is D) the black vessel will cool faster because a black surface radiates heat faster than a polished one. ✅
Here’s why:
Every object loses heat to its surroundings in three ways: conduction, convection, and radiation. In this problem, the main difference is the color of the surface, so we’re focusing on radiation, which is heat lost in the form of electromagnetic waves.
Now, some key things about radiation:
Dark or black surfaces are good emitters of heat. They release heat energy very efficiently.
Polished or shiny surfaces are poor emitters. They reflect a lot of heat instead of giving it off.
So in our vessels:
The blackened vessel gives off heat faster → water inside cools faster.
The polished vessel holds onto heat longer because its shiny surface doesn’t radiate as much.
That’s why D is correct.
Step 2: Why the other options are wrong
Option A says: “The polished surface is a good radiator.” Wrong. Polished surfaces are bad radiators. That’s literally the opposite of what physics teaches about radiation.
Option B says: “Polished vessel absorbs less heat from the room.” This is misleading. Whether it absorbs heat from the room doesn’t matter here because the main heat transfer is from the hot water to the surroundings, not the other way around. Even if it absorbed less, it wouldn’t make it cool faster.
Option C says: “Black reflects heat better.” Wrong again. Black absorbs heat very well and also radiates it. Reflection is what shiny surfaces do.
So D is the only one consistent with physics.
When light falls on a surface three things happens some portion of the light is reflected while some are absorbed and some transmitted. The polished vessel reflects a wide portion of the light, leaving a small portion been transmitted or absorbed while the blackened surface reflects little of the light thereby leaving a huge portion been transmitted and absorbed D is the correct answer' stephans law '.
