<p>^Good luck to you seniors! I hope you guys get 800s :)</p>
<p>i think we have discussed all the relatively challenging ones, no?</p>
<p>no we have not. I still remember one question where two blocks approach each other. One has a northward direction and the other eastward I think. When they collide they stick together (perfect inelastic collision). I think it was asking about whether liner momentum, kinetic energy and another thing were conserved. I think just linear momentum was conserved?? (I believe “Only II” was the answer). Do u remember such a question?</p>
<p>^I remember it was mechanical energy and linear momentum–K.E. wasn’t conserved, but Mech E is always conserved</p>
<p>There was also another question…what happens when you tighten a guitar string?</p>
<p>ur right that was the other option, but is mechanical energy really conserved in such collisions? I thought that if kinetic energy wasnt conserved, then mech. energy would not be conserved either.</p>
<p>Compiled Answers
-Universe expansion: red shift + something else, I & II
-Oil drop: calculate electron charge
-Ice cube -50 C to 150 C:
… _<em>/
… /
.</em>/
/
-Initial velocity 30 m/s, v and a at apex: 0 m/s, -10 m/s^2
-Initial velocity 30 m/s, v and a final: 30 m/s, -10 m/s^2
-X and Y collision: need to know masses (was this the same as ratio of the masses?)
-Thermal equilibrium: increase entropy
-Insulator/conductor: glass and aluminum
-Starting a fire: converging lens
-Cop car moving: fA < f0, fB > f0
-People moving: fA > f0, fB < f0
-Heavy ball versus lighter ball: I put ratio of V to SA was smaller in the larger ball
-Lightest particle: electron (I just googled this)
-Magnification of diameter of coin: 6 (choice A)
-Ball going east, force applied to it: went east, curved, and carried on this way diagonally southwest
-Why doesn’t moon crash into earth: Constant gravitational pull, but the velocity keeps it from crashing
-Electroscope, what was the rod’s charge: negative
-Which one didn’t have a 1/r^2 graph: potential energy of charge
-Maximize magnetic force: I, II, and III (velocity of particle, charge of particle and magnitude of magnetic field)
-Moon and earth gravity, change in mass: no change (arghhhh I got tricked T.T)
-Moon and earth gravity, change in force: 160 N
-20 ohm and 40 ohm resistor: h/2
-Changing induced current: I, II, and III (area, resistance, rate of change of field)
-Charge and circle, change in potential: I and II
-Charge and circle, MAX change in potential: I
-Charge and circle, no work: III
-Two samples: 50 degrees C
-Buzzing noise: ???
-P/V graph for heat engine: II and III
-Normal force: cart on the bottom (point A)
-Scientist: Galileo
-Graph of K.E., which of these is 0: none of these
-2m and 3m carts: tension is 2m
-Greatest normal force on cart: at bottom
-Greatest acceleration for pendulum: at the greatest displacement (missed this one )
-Greatest tension on swing: at the bottom
-Election through magnetic field, force going upward: Idk, but it was easy
-Index of refraction: ???
-Set of numbers, accelerating: 1, 4, 9, 16
-Set of numbers, force opposing velocity: numbers decreasing
-Set of numbers, K.E. of sliding block: 1, 4, 9, 16
-Inelastic collision: mech e and linear momentum conserved* debatable?
-Guitar string: ???
-Charge with highest potential: the one that was farthest up
-Which refraction/reflection line is incorrect: the one at the bottom going from the glass back into the air</p>
<p>^45 questions so far, anyone remember anything else? Even the easy ones?</p>
<p>ahhhh, i put 1,2,3,4 for the KE one. I was debating between that and the exponential one. I did it based on TE = PE + KE and thought it would be a linear transformation.</p>
<p>^Hmmm. That depends on whether or not it was looking at velocity or KE. I don’t remember. Anyone?</p>
<p>The one with the incident light on the glass surface was E. It is possible for the light to bounce off the bottom edge of the glass and go back up. You have that answer marked incorrectly on the compilation list.</p>
<p>^That’s actually what I meant, but I’ll change it bc it sounds confusing
Compiled Answers
-Universe expansion: red shift + something else, I & II
-Oil drop: calculate electron charge
-Ice cube -50 C to 150 C:
… _<em>/
… /
.</em>/
/
-Initial velocity 30 m/s, v and a at apex: 0 m/s, -10 m/s^2
-Initial velocity 30 m/s, v and a final: 30 m/s, -10 m/s^2
-X and Y collision: need to know masses (was this the same as ratio of the masses?)
-Thermal equilibrium: increase entropy
-Insulator/conductor: glass and aluminum
-Starting a fire: converging lens
-Cop car moving: fA < f0, fB > f0
-People moving: fA > f0, fB < f0
-Heavy ball versus lighter ball: I put ratio of V to SA was smaller in the larger ball
-Lightest particle: electron (I just googled this)
-Magnification of diameter of coin: 6 (choice A)
-Ball going east, force applied to it: went east, curved, and carried on this way diagonally southwest
-Why doesn’t moon crash into earth: Constant gravitational pull, but the velocity keeps it from crashing
-Electroscope, what was the rod’s charge: negative
-Which one didn’t have a 1/r^2 graph: potential energy of charge
-Maximize magnetic force: I, II, and III (velocity of particle, charge of particle and magnitude of magnetic field)
-Moon and earth gravity, change in mass: no change (arghhhh I got tricked T.T)
-Moon and earth gravity, change in force: 160 N
-20 ohm and 40 ohm resistor: h/2
-Changing induced current: I, II, and III (area, resistance, rate of change of field)
-Charge and circle, change in potential: I and II
-Charge and circle, MAX change in potential: I
-Charge and circle, no work: III
-Two samples: 50 degrees C
-Buzzing noise: ???
-P/V graph for heat engine: II and III
-Normal force: cart on the bottom (point A)
-Scientist: Galileo
-Graph of K.E., which of these is 0: none of these
-2m and 3m carts: tension is 2m
-Greatest normal force on cart: at bottom
-Greatest acceleration for pendulum: at the greatest displacement (missed this one )
-Greatest tension on swing: at the bottom
-Election through magnetic field, force going upward: Idk, but it was easy
-Index of refraction: ???
-Set of numbers, accelerating: 1, 4, 9, 16
-Set of numbers, force opposing velocity: numbers decreasing
-Set of numbers, K.E. of sliding block: 1, 4, 9, 16
-Inelastic collision: mech e and linear momentum conserved* debatable?
-Guitar string: ???
-Charge with highest potential: the one that was farthest up
-Which refraction/reflection line is incorrect: the one at the bottom going through the glass out into the air (choice E)</p>
<p>
</p>
<p>I’m pretty confident it asked KE vs time.</p>
<p>I had no idea what to do with the guitar question. I tried: sqrt(tension x L/m) = lamba x freq.
It obviously did not work. Anyone have any idea how to solve that problem.</p>
<p>@MC: it was definitely KE. However, the only variable that was actually chaning was v^2. Hence, I think we could have treated it as a velocity by time graph.</p>
<p>For the guitar string question I put wavelength. The tension was obviously not going to stay constant, and if you tune a guitar string, the frequency of its vibration is, by definition, going to change as well.</p>
<p>Yes, there was one also about if the earth’s radius were doubled, but its mass were the same, what would be the acceleration due to gravity on the surface?
It was g/4 I suppose.
There was also one which I just remember vaguely. It was about a pendulum and its period when it is brought to a planet where g=5 and to another planet where g=20. I guess the period on the 1st planet would be sqrt(2)*T and in the second T/sqrt(2).
Another question I remember, even though I dont remember if it has already been taken into account. The one of the horizontal spring on a frictionless table. If its stretched a distance d, then its velocity at the equilibrium position will be v. What will be its velocity at the same point if its stretched 2d? I put 2v.
For the guitar string question I put wavelength and frequency (II and III), because by tuning a guitar string u are changing its pitch (frequency), and since sounds velocity is constant its wavelength must change too.</p>
<p>Ive just remembered another one, about the frequency of the beats. It had to be the difference between the frequencies of the two different sources of sound or something like that.
edit: another 1. The one about the string, standing waves formed and the scientist taking pictures of it. It asked about what picture was impossible, I believe. I just left it blank. Any ideas?
edit: There was one about a rocket traveling to a star and coming back at relativistic speeds. I think the time measured by someone on earth was longer.
edit: another one about a 31P atom which had I believe 15 neutrons and was electrically neutral. Answer was 16 protons and 16 electrons.
edit: there was also another one regarding the slit experiment. Answer was: there are dark and light intervals because light interferes with other light rays coming from different parts of the slit.</p>
<p>53 questions</p>
<p>I thought the guitar string question involved which ones would stay constant.</p>
<p>^^I agree with everything you have said and </p>
<p>the waves one, the one that was impossible was the one where the nodes and antinodes were not in their places</p>
<p>double slit experiment one: the fringes(or whatever it referred to) are formed/what happens is that the waves interfere constructively</p>
<p>What exactly did the guitar string question entail? I remember it being a I II III question asking which ones stayed constant as you tightened the knob of a guitar string. The three options were tension, frequency, and wavelength.</p>
<p>Am I mistaken?</p>
<p>^It might have been constant, i don’t exactly remember</p>
<p>Because I distinctly thinking that none of them would stay constant, but “none” wasn’t an answer choice. So I reasoned that wavelength would somehow stay the same.</p>