<p>Here are some questions I get stuck while reviewing. I appreciate your assistance.</p>
<ol>
<li><p>A scientist meaasures the mass of a sample to an accuracy of 1%. Which of the following is most likely the mass he measured?
a) 44.4g b) 44g c) 4.4g d) 4g e) 0.4g</p></li>
<li><p>Which of the following is not a formulation of the Second Law of Thermodynamics?
a) heat flows spontaneously from a hotter body to a colder body
b) the internal energy of a system doing work decreases
c) the entropy in the universe is increasing
d) there is no such thing as a heat engine with 100% efficiency
e) time flows in the direction of entropy increase</p></li>
<li><p>Which of the following best explains why 2 protons in the nucleus of an atom don't push away from one another in accordance with Coulomb's Law?
a) Rutherford's model of the atom
b) other neutrons in the nucleus
c) wave-particle duality
d) conservation of charge
e) length contraction</p></li>
</ol>
<p>Why do you think the answer to 2) is E, undefined123?
According to Princeton Physics, all C,D,E belong to the 2nd law of thermodynamics. A, however, is the 0th law, and B is the 1st law. So I’m rather confused.</p>
<p>I think the answer to number is 2 is B because that is a formulation of the 1st law. A is zeroth lawish but it is also a formulation of entropy. There was an actual SAT physics question like this either in the blue book or in the older blue book.</p>
<p>These are not very clean questions. Number 1 is just dumb.</p>
<p>2 is E because entropy is always increasing, and since time can be perceived to be flowing in a positive direction (when you draw it on a graph, the number line proceeds as t=1, t=2 and so on). So if entropy is always increasing and time is always increasing, then they are traveling in the same direction. </p>
<p>3 is B because of the binding force between the protons and the neutrons within a nucleus, this one isn’t automatically obvious, but can be easily deduced by eliminating the other answer choices. It’s obviously not Rutherford’s model of the atom cause that has nothing to do with binding forces. Clearly not wave particle duality since nothing in this question involves subatomic particles moving in wavelike patterns. Conservation of charge, if anything, is more a chemistry concept in redox and balancing equations over nuclear chemistry/physics. Finally, length contraction is some seriously messed up relativity concept that discusses the fact that your length goes to 0 and your mass goes to infinity when you get to the speed of light and how the proportional scaling of that. So by simple elimination, we can deduce that the only thing related to this subject is the neutrons that provide the binding force within the atom.</p>
<p>2 is actually B. Internal energy decreasing from work is a product of the First Law of Thermodynamics. It’s given from the equation ∆U = Q - W. For those of you saying it’s E, that is incorrect. Time flows in the direction of entropy increase (from the 2nd law of thermodynamics). The point of that law is that entropy in the universe is increasing, so time will flow in the manner that it will continue to increase.</p>
<p>Edit: 2 is not A because that is from the second law. By energy flowing from hot to cold, some energy is released. Although the system’s entropy has decrease, the surroundings’ entropy has increased, resulting in a net increase in entropy.</p>
<ol>
<li>Which of the following is not a formulation of the Second Law of Thermodynamics?
a) heat flows spontaneously from a hotter body to a colder body It is - heat does flow from hot to cold according to the second law
b) the internal energy of a system doing work decreases That’s literally the equation U=Q+W
c) the entropy in the universe is increasing That’s an aspect of the second law
d) there is no such thing as a heat engine with 100% efficiency That’s also another aspect of the second law - heat engines
e) time flows in the direction of entropy increase Never heard of that. Hence, it’s not part of the second law.</li>
</ol>
<p>Just cause you haven’t heard of it, doesn’t mean that’s incorrect. The equation U = Q+W is from the FIRST law of thermodynamics, this question is asking about the SECOND law of thermodynamics.</p>