# Isaac Physics

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Thread starter 1 month ago
#1
Im getting frustrated with this website because I dont know whether Im doing the questions right, and they are annoying about sig figures.
Can anyone help me with some of the questions in Dynamics, Kinematics and Resistors. Thanks so much!!
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1 month ago
#2
Yeah post up the questions and your working so far and someone will try and help.
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Thread starter 1 month ago
#3
Ok update - I managed to complete more questions,( just because I was right all along, it was the significant figures part that was hard to enter my answers and misunderstanding how I should type them up)

But there are questions that I just dont know any more and keep on getting the same answers

Indecisive Gas - Part B
https://isaacphysics.org/questions/a...6-ea6f1431eb49
Cells in reverse
https://isaacphysics.org/questions/c...6-ea6f1431eb49
Cliff reflection
https://isaacphysics.org/questions/c...6-ea6f1431eb49

Two Microphones
https://isaacphysics.org/questions/t...1-9f886f2169db
Which fuse to use
https://isaacphysics.org/questions/w...1-9f886f2169db
Two transformers
https://isaacphysics.org/questions/t...1-9f886f2169db

Tug o war - This question I do understand , as the resultant force should be 0. So I put yB=xA=0 as the equation but its wrong
Or yB-xA=0 Idk.....
https://isaacphysics.org/questions/t...1-9f886f2169db

Ok... I know they are a lot of questions, but at this point I feel really stupid struggling with them, being 5 months out of practice, even if it looks "easy" if u see them (idk!!)

But if anyone has solutions and can work them out I will be extremely grateful thanks
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1 month ago
#4
Tug o war wants you to rearrange into x=(something)... the equation editor they've got is a bit clunky tho (IMHO)

two transformers - you've got two transformers both stepping down by the same ratio to give an overall ratio of 240/115000
so it's like finding the number that multiplied by itself will give you 240/115000
1
1 month ago
#5
For the indecisive gas part B, remember that pV/T = constant. Also when I did this they only accepted the units dm^3 for some reason, so if you work in SI units just convert it.

For the microphone thing, A is treated as a point source, so the sound waves spread out uniformly in all directions.
Last edited by Despaxir; 1 month ago
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1 month ago
#6
For the cells in reverse you have to remember that the voltage around a closed loop is dependent on the cell's polarity. Take the smaller line as negative, bigger line as positive and then use your knowledge of conventional current/electron flow to work it out. Also know V=IR, so I is proportional to V in a circuit.
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Thread starter 2 weeks ago
#7
(Original post by Despaxir)
For the indecisive gas part B, remember that pV/T = constant. Also when I did this they only accepted the units dm^3 for some reason, so if you work in SI units just convert it.

For the microphone thing, A is treated as a point source, so the sound waves spread out uniformly in all directions.
Thanks. Sorry for the late response. I got the answer 3.73 dm^3, which I think is the correct answer, but Im having a problem with the significant figures as Isaac Physics repeatedly said it needs to be fixed. I did it but its still not giving me the correct answer

Edit - i did my calculations again and I got 2.6 dm^3 this time. Dont know if this is right though, but i know my previous answer must be wrong.

I did

P1 v1/T = constant (initial pressure and volume)

P2 v2/T =constant (final pressure and volume)

For this question, I assumed the constant temoreture is the same = 100degrees or in this case 373, from part A

So i did
130000Pa *2dm^3/373 = 100000Pa*V2/373
Then i rearranged it to equal V2 (final volume) if this makes sense.

Please check my working out, as im not really sure if i did this right??? Thanks so much btw 😁
P.S - Significant figures still a problem😅
Last edited by world2change; 2 weeks ago
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