A thermodynamic system undergoes a process in which it's internal energy decreases by 500J?

Question

If at the same time 220 J of work is done on the system, find the energy transformed to or from the system as heat?

I need help.. this question is bugging me.

Answer 1

I think such questions bug you because you equate Internal energy with heat. Work and heat both are energies in transit for any process. Think like this, if 220 J work is done on the system its energy would have increased by 220 J. But instead its internal energy has decreased by 500 J. So only way this is possible is if [220 + 500] J = 720 J amount of energy leaves the system as heat. If you like to work with formula then

U = Q - W

here U = -500; Q unknown: W = -220

-500 = Q - (-220)
-500 = Q + 220

or Q = -500-220 = -720 J

So the system has lost 720 J as heat

Answer 2

What you've defined is a root cellar. Thermal mass purely averages out the temperatures no longer produce chilly. notwithstanding as a warmth sink, even if you used diamond (maximum warmth conductivity fabric conceivable) all you're doing is equalizing the temperature interior the hollow area with the temperature outdoors of the gadget. undergo in concepts if it may sink warmth from the hollow area, it is going to also sink warmth from outdoors the gadget and that's floor area on the outdoors is way more beneficial then the exterior area contained in the hollow area. Your lateral questioning desires to flow both strategies in the previous it receives it properly. for sure, in case you position the entire gadget in an ecosystem without warm temperature then it is going to surely be chilly contained in the hollow area yet what good is a refrigerator that purely works at the same time as that's interior a refrigerator?