An ideal heat engine operates of fixed difference of temperatures between hot and cold reservoirs, say 100k. what will provide greater efficiency: operation with the hot reservoir as hot as possible, or operation with a cold reservoir as cold as possible?

To solve this problem we will apply the concepts given for the efficiency of an engine which is given as

Where

= Temperature of the cold reservoir

= Temperature of the hot reservoir

The efficiency maximum would be given only if

Replacing this value we have

Therefore: Cold reservoir as cold as possible provide the greater efficiency.

resonant frequency

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.