Does anyone know if the spectral classes might come up tomorrow? It's never come up in past papers so I haven't particularly revised it but wondering if I should learn it now?
Does anyone know if the spectral classes might come up tomorrow? It's never come up in past papers so I haven't particularly revised it but wondering if I should learn it now?
From the examiner's report for the IAL paper: The question refers to simple harmonic motion, which may or may not be damped. If undamped, total energy would remain constant (no answer key), but this is not a condition of simple harmonic motion. In general, none of the energies stated must remain constant, and so the correct response is B.
Thank you, but the mark scheme says the answer is D?
Okay, I was thinking the same thing as well. I'm having trouble understanding this quesiton as well if anyone could help out
I'm working on this paper at the moment too and my (nowhere near perfect!) answer for this question is:
When the can is heated, the internal energy of the gas increases. The molecules gain kinetic energy, so there are more frequent collisions with the walls of the container, increasing the rate of change of momentum. This leads to an increased force on the container and an increased pressure. The liquid inside the can would also evaporate, increasing the pressure further. The can would explode before it reached 900K as its maximum temperature (excluding the evaporated liquid) is 870K, and the increased number of gas molecules would further decrease its maximum temperature before it explodes.
ooh I just did this question today and my teacher had to explain it to me! Imagine a spring system being set into an oscillation, at maximum amplitude all the total energy is PE while all the total energy at 0 amplitude is KE. Consider the spring then at 0 amplitude in both scenarios. KE = 1/2 mv^2. Since it is SHM, v max = Amplitude x omega. When the amplitude has halved, v^2 = (1/2 amplitude)^2 x omega^2, hence the maximum KE has decreased by a factor of 4 and thus the total energy of the system. Since it is asking for a ratio, you do 1/(1/4) to get 4
I was thinking along the same lines as you - do you know why the answer can't be D? Thanks!
I'm not entirely sure but I reckon it's because that answer doesn't explain why it is expanding at a faster rate? It could be younger but still slowing down I suppose...
I'm working on this paper at the moment too and my (nowhere near perfect!) answer for this question is:
When the can is heated, the internal energy of the gas increases. The molecules gain kinetic energy, so there are more frequent collisions with the walls of the container, increasing the rate of change of momentum. This leads to an increased force on the container and an increased pressure. The liquid inside the can would also evaporate, increasing the pressure further. The can would explode before it reached 900K as its maximum temperature (excluding the evaporated liquid) is 870K, and the increased number of gas molecules would further decrease its maximum temperature before it explodes.
Hmm, I would put the momentum stuff too (even though it isn't mentioned in the MS) but now I understand the latter part of the explanation. Thank you once again !
Hmm, I would put the momentum stuff too (even though it isn't mentioned in the MS) but now I understand the latter part of the explanation. Thank you once again !
Basically the formula for total energy is 0.5.k.A^2, so use that to find the initial Et and the final Et, and divide them (ignore k as it's constant)
If you were using the formula E= 0.5kA^2, what value should be used for k?
Any value (I use 1 for convinience) as long as you use the same value in both the initial and final energies because it's a constant so it's effect will be cancelled out
Any value (I use 1 for convinience) as long as you use the same value in both the initial and final energies because it's a constant so it's effect will be cancelled out
Would that apply to all questions? What if we were given the amplitude and asked to calculate total energy?
Question 18 (d) asks you to calculated efficiency, I don't understand why the total possible output power (denominator) is 2200+3100 instead of just 3100?
2200MW is given as a total output power and the value we calculate, 3100, is the "rate at which energy is removed from the reactors"?