## PHysics Qpack + BioQpack 2: a couple questions

lotus0618
Posts: 149
Joined: Sun Dec 29, 2019 5:47 pm

### PHysics Qpack + BioQpack 2: a couple questions

Physics Qpack:
1) question 100: why not B? I thought the energy released comes from the attractive potential energy of the atoms

2) question 101: I chose speed (answer C) because mass is not a variable in determining speed. However, looking back, the equation for Force (kq1q2/r2) doesn’t have mass either. Between A and C, how would you decide which one is correct on the test?

3) question 111: So I know how to solve it: like I figured out that v= square root of 2gh. I then do the ratio of the 2 velocities with a height of 10 and of 20, which will give me the square root of 2 over 2. This answer is different from all of these answers here. What did I do wrong here?

4) question 116: Okay so I get the values of 18 and 4N, but how could you even get a magnitude of 8 or 12? Why does the question refer to any values within this range? I’m so confused by this seemingly simple question

Bio Qpack volume 2:
55) how can I prevent myself from making this mistake? I feel like I’d miss this again on the test. This is like a CARS passage. The question asks for why the scientists INITIALLY hypothesized NOT WHY they decided that the pathogen caused the disease after doing some experiments.

71) I didn’t answer this question correctly cause I misinterpreted the question. AAMC purposely made the wordings so confusing. How can I improve this?

Thank you!
NS_Tutor_Yuqi
Posts: 34
Joined: Fri May 29, 2020 11:43 pm

### Re: PHysics Qpack + BioQpack 2: a couple questions

Physics
100: This question directs you to the passage, so the first step is to find which part of the passage describes why there is so much energy released as a nucleus splits. Specifically, it states that "There is a large electrical repulsion between these two fragments that causes them to move apart and gain kinetic energy", which provides support for D. Although there is an attractive strong nuclear force keeping the atoms together originally, it is only because this force is overcome by the repulsive force that fission occurs.

101: Since we already know that acceleration will be different for the two fragments, we can conclude that their speeds will also be different since they will be accelerating at different rates. When evaluating A, like the answer explanation said, the first thing you should think of is Newton's 3rd law, where forces are equal and opposite to one another. Therefore, A is the best answer.

111: All that you needed to do differently is divide v20 by v10, instead of the other way around. Since all the answer choices ask for the factor by which it is slower, you know that you want the ratio to be greater than 1 (since starting from a lower height means that the velocity will be slower). If you look at the AAMC answer explanation, they also originally get an answer of root 2 over 2 since they are taking the square root of 1/2. However, they then flip that around in order to arrive at the final answer of root 2 (D).

116: You can get the answers within the range when the forces are not directly parallel to each other. In other words, the two force vectors can meet at an angle, which means that the resulting force is somewhere between the minimum and maximum forces that can be achieved (in order to solve for this, you'll have to multiply the force vectors by the sin or cos of the angle). The range is determined through adding the two values together or subtracting them from one another, which results in 4N and 18N. This means that the net force cannot exceed 18 N or be lower than 4N, but can be anywhere in between depending on the angle.

Bio
55. A lot of science passages end up feeling like CARS since all the information you need to solve the question can be found in the passage. The best way to not miss problems like this in the future is to carefully read the question and figure out exactly what the question is asking. It's also important to remember that the hypothesis is made before any experiments are done.

71: "Not" questions are especially tricky since you basically have to think about what doesn't answer the question. If you use highlighting, it may be helpful to highlight the "not" or "except" in questions to constantly remind yourself of them. Other than that, continuous practice with AAMC problems will also help get you in the mindset of AAMC.