Answer:
D. The temperature does not change during a phase change because the average kinetic energy does not change. Therefore, the potential energy in the bonds between molecules must change.
Explanation:
When there is a change of state (for example, from solid into a liquid, as in this example), when energy is added to the system, the temperature of the substance does not change.
The reason for this is that the energy supplied is no longer used to increase the average kinetic energy of the particle, but instead it is used to break the bonds between the different particles/molecules. For instance, since in this case the substance is changing from solid to liquid, all the energy supplied during the phase change is used to break the bonds between the molecules of the solid: when the process is done, all the molecules will be free to slide past each other, and the substance has turned completely into a liquid.
The bonds between molecules store potential energy: therefore, this means that the energy supplied during the phase change is not used to change the kinetic energy, but to change the potential energy in the bonds between the molecules.
Answer:
The moon has no atmosphere
Explanation:
The temperatures on the surface of the Moon vary much more than those on Earth because the moon has no atmosphere (third answer in the list), and therefore there are no molecules that could retain residual heat and make the change from day to night a softer transition.
Answer:
(a) 
(b) P = 0.816 Watt
Explanation:
(a)
The power radiated from a black body is given by Stefan Boltzman Law:
where,
P = Energy Radiated per Second = ?
σ = stefan boltzman constant = 5.67 x 10⁻⁸ W/m².K⁴
T = Absolute Temperature
So the ratio of power at 250 K to the power at 2000 K is given as:
(b)
Now, for 90% radiator blackbody at 2000 K:
<u>P = 0.816 Watt</u>
Answer:
B) Power is the rate at which work is done
