Question

Which statement describes the relationship between energy and entropy in the universe?

Answer 1

In fact, entropy of an isolated system never decreases (2nd law of thermodynamics), unless some external energy is provided in order to "restore" order in the system and decrease its entropy.

(note that when external energy is added to the system, it is no longer "isolated").

*This is only true if the question is referring to a certain system within the universe. If we are considering the universe itself as the system, then this option is no longer correct, because no external energy can be provided to the universe, and since the universe is an isolated system, its entropy can never decrease. If we are considering the universe itself as the system, none of the options is true.

Answer 2

Answer:

Energy must be created to increase entropy.

Explanation:

The choices for this quetion are

• Energy must be destroyed for entropy to be constant.
• Energy must be decreased for entropy to be constant.
• Energy must be added to decrease entropy.
• Energy must be created to increase entropy.

According to physics, entropy can be defined as the measurement of randomness in a system. It depends of the observations at the moment, when we talk about entropy, the time past before to reach the current state, doesn't matter. With entropy, all that matters is the now.

Now, energy is the potential to do some work, that is, to get movement in a system. That meas, to molecules move, we need to add energy, that's how it works. So, in thermodynamics, when we increase the temperature of a system, the randomness also increse, that is, the entropy increase, because the increase of temperature is related to adding energy. So, basically, more energy increases entropy, that's why entropy is always in one direction, from a current state to another more random state, more disorder.

So, when if we say that we add energy to decrease entropy, that's wrong, because the energy increases the degree of random activity of the particles involved.

Therefore, the right answer is the last choice: Energy must be created to increase entropy.

However, this true statement must be rewritten, because according to thermodynamics, energy cannot be created or destroyed, just can be transformed. So, we are talking the last choice as energy transformation.

It's important to say that other options aren't true because, as we said before, entropy doesn't decrease, and it doesn't remain constant.