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VCE Physics Question Thread!
Rachelrachel:
--- Quote from: ArtyDreams on July 25, 2021, 07:00:41 pm --- you have to make sure that you convert the tonnes to kilograms.
--- End quote ---
1 tonne = 1000 kg. Therefore converting to kg doesn't change the actual digits of the answer, only its magnitude (the mass works out to be 14167 kg instead of 14.17 tonnes). I'm still stuck on how the textbook gets an answer of 4200 kg.
ashmi:
--- Quote from: Rachelrachel on July 25, 2021, 05:34:02 pm ---Hey guys, I'm completing some Unit 1&2 conservation of momentum questions and am really confused by this one.
"a railway wagon of mass 2.5 tonnes moving along a horizontal track at 2 m/s runs into a stationary engine and is coupled to it. After the collision, the engine and the wagon move off at 0.3 m/s. What is the mass of the engine alone?"
I used this formula:
m1u1 + m2u2 = m3v3
to obtain:
2.5*2+0 = (2.5+m)*0.3
This resulted in m=14.17 tonnes. However, my textbook says that 4.2 tonnes is correct. I have no idea how to obtain this answer.
Can anyone offer any insight?
--- End quote ---
First things first, I don't see anything wrong with your working out here. Just as Arty has mentioned above, it would be preferable if you kept the momentum to kg/m/s (just in case you lose track of units). I believe your answer (14.17 tonnes) is correct.
parieeelol:
Hey guys - I've been stuck on this question for a while now, and I believe it's asking for the angle of emergence, but I have no idea how to calculate it and the solutions aren't making sense. (Unit 4 Physics, AOS1)
The angle of incidence was calculated to be 48 degrees, and angle of refraction as it enters the prism was 28.6 degrees. I used Snell's Law for both. But other than that, I have no idea how to tackle this question and would appreciate any help.
SmartWorker:
--- Quote from: parieeelol on August 11, 2021, 12:29:21 pm ---Hey guys - I've been stuck on this question for a while now, and I believe it's asking for the angle of emergence, but I have no idea how to calculate it and the solutions aren't making sense. (Unit 4 Physics, AOS1)
The angle of incidence was calculated to be 48 degrees, and angle of refraction as it enters the prism was 28.6 degrees. I used Snell's Law for both. But other than that, I have no idea how to tackle this question and would appreciate any help.
--- End quote ---
Hi, i tried the question, i don't know if my solution is correct but i hope this at least helps a bit.
So yep the angle of refraction = 28.6 degrees.
Then notice: the triangle is equilateral. Make a right angled triangle (should be able to do this as the dotted line is the normal line) and then you can solve from there.
miyukiaura:
Hey guys, I just had a question about refraction: why is it that when light refracts into a different medium, its velocity and wavelength change but frequency remains constant? I would have thought that frequency is inversely proportional to wavelength so as e.g. wavelength increases, frequency decreases?
Thanks!
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