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 0 Click here to jump to the problem! OptimusPrime2017-04-08 04:47:54 This is really helpful! The point of fastest velocity of the rope shaking happens when crossing the y-axis, which is maximum E amplitude in this case.Click here to jump to the problem!
 1 Click here to jump to the problem! OptimusPrime2017-04-08 02:27:42 (A) and (B) are maybes so far.\r\n(C) - No, we are dealing with PROTONS instead of the usual electrons. So the mass of the electron shouldn\'t come into play at all.\r\n(D) - Maybe.\r\n(E) - No, since after this collision the photon must lose energy. Recall that higher frequency means higher energy. So if we are losing energy, that means our frequency has decreased, and since frequency and wavelength are inversely related, the wavelength has increased. \r\n\r\nIf you remember the Compton equation then you\'ll find as Yosun wrote that change in wavelength equals the Compton wavelength. But, where can we extract any numbers from that?! We can\'t, so (A) and (B) are out.\r\n\r\nThat leaves (D). On top of that, (D) has the correct dimensions. [h/mc] = (M*(L^2) / T) / (M*L / T) = L. Length as in wavelength.Click here to jump to the problem!
 2 Click here to jump to the problem! OptimusPrime2017-04-08 00:55:51 I\'m confused. Choice (E) resembles the function y = $\\frac{1}{x^2}$ which has positive concavity, not negative like the graph shows.Click here to jump to the problem!
 3 Click here to jump to the problem! OptimusPrime2017-04-08 00:36:49 For (B), plugging in $\\\\\\\\theta$ = 90 degrees gives 90/2 = 45 degrees. Then, cos(45) = $\\\\\\\\frac{\\\\\\\\sqrt{2}}{2}$. It also has the correct dimensions. How else do we eliminate (B)?Click here to jump to the problem!
 4 Click here to jump to the problem! liuyuhang5992017-04-04 14:43:16 Your answer is correct, $\\\\\\\\1s^2$ gives two possible states ( |+-> - |-+>) the singlet state, and ( |+-> +|-+> ) the triplet state. And because electron is fermion, only the antisymmetric singlet state is allowed.Click here to jump to the problem!
 6 Click here to jump to the problem! dipanshugupta2017-03-31 10:12:40 Here \\\'s my method, using \\makebf{Picking Numbers}. Pick a time, say 12, because it is divisible both by 24 and 36. In 12 mins, \\alpha decays \\frac{1}{4} and \\beta decays \\frac{1}{6} . Add them up to get \\frac{5}{12} , which is close to half. Take a time little more than 12. Hence, 14.4 minutes. Pick C. Click here to jump to the problem!
 8 Click here to jump to the problem! dipanshugupta2017-03-30 07:35:09 If you have ever studied the Harmonic Oscillator, you\'ll know that $a$ and $a^+$ are Creation and Annihilation operators, i.e, they increase or decrease one quanta of Energy. \r\nI. The commutator gives one negative quanta of energy. \r\nII. Wrong if III is correct. \r\nIII. Definitely, as per above discussion. \r\n\r\nThus, answer is C. \r\n\r\n(I have taken a QFT class so it was easier for me but it\'s in QM too). Click here to jump to the problem!
 10 Click here to jump to the problem! dipanshugupta2017-03-29 10:45:02 How do you get the $B cos(\\omega t)$ term for $B.dA$? Click here to jump to the problem!
 11 Click here to jump to the problem! dipanshugupta2017-03-29 10:02:01 Simpler answer. Beta Decay is a Weak Interaction. Weak Interactions are Parity Violating. Parity is a Reflection invariance as $P^\' (\\vec{x},t) \\Rightarrow P ( - \\vec{x},t)$. Hence, problem solved. Click here to jump to the problem!
 12 Click here to jump to the problem! dipanshugupta2017-03-29 08:55:09 WoolfianOperator, you used $v_2$ as $0.6v$ when you should\\\\\\\'ve used it as $-0.6v$, since the He atom is travelling in the opposite direction after collision. Click here to jump to the problem!
 13 Click here to jump to the problem! NervousWreck2017-03-28 17:21:16 The most straitforward is to draw a PV diagram where an adiabatic expansion would be a curve, which is steeper than an isoterm. Therefore one immediately notices that the E is False.Click here to jump to the problem!
 14 Click here to jump to the problem! NervousWreck2017-03-28 11:00:04 also disregard people trying to find a mistake in this solution. this is the fastest one.Click here to jump to the problem!
 17 Click here to jump to the problem! NervousWreck2017-03-28 09:45:40 This is a very complicated problem due to the lack of time. However the fasters solution as I see it is the following\r\n$1/(\\sqrt N/2)=0.02$. Here rate is 2, which is multiplied by 1%. On the LHS is an error of poissson distribution with 2 measurements per second taken into account. The solution gives N = 5000, which now corresponds to seconds.Click here to jump to the problem!
 22 Click here to jump to the problem! blabla00012017-03-25 09:10:25 Notice that the char. equation for this matrix is $\\lambda^3-1$Click here to jump to the problem!