Materials that are poor conductors of thermal energy are called.....
1 answer:
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Answer: 4.8 s
Explanation:
We have the following data:
the mass of the raft
the force applied by Sawyer
the raft's final speed
the raft's initial speed (assuming it starts from rest)
We have to find the time
Well, according to Newton's second law of motion we have:
(1)
Where is the acceleration, which can be expressed as:
(2)
Substituting (2) in (1):
(3)
Where
Isolating from (3):
(4)
Finally:
As per Stefan - Boltzmann law we know that
1. Power radiated in the form of electromagnetic energy by an object at nonzero temperature.
2. Every object at absolute (kelvin) temperature t will radiate electromagnetic waves.
3. This radiation is typically in the infrared for objects at room temperature, with some visible light emitted for objects heated above 1000 k.
4. The formula governing the rate of energy radiation from a surface is given by ,
where p is the thermal power (also known as the heat current h).
Thermal radiation in visible light can be seen on hot metalwork. Its emission in the infrared is invisible to the human eye. Infrared cameras are capable of capturing this infrared emission.
Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produce electromagnetic radiation.
Examples of thermal radiation include the visible light and infrared light emitted by an incandescent light bulb, the infrared radiation emitted by animals that is detectable with an infrared camera, and the cosmic microwave background radiation. Thermal radiation is different from thermal convection and thermal conduction—a person near a raging bonfire feels radiant heating from the fire, even if the surrounding air is very cold.
Sunlight is part of thermal radiation generated by the hot plasma of the Sun. The Earth also emits thermal radiation, but at a much lower intensity and different spectral distribution. The Earth's absorption of solar radiation, followed by its outgoing thermal radiation, are the two most important processes that determine the temperature and climate of the Earth in most climate models.
So the correct answer which is applicable here will be
This formula applies to any object of total surface area a, kelvin temperature t, and emissivity e
here