/r/HomeworkHelp
Need help with homework? We're here for you! The purpose of this subreddit is to help you learn (not complete your last-minute homework), and our rules are designed to reinforce this.
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- [Grade 8 Math: Quadratic Equations] How to factorise ax2 + bx + c?
- [University Chemistry: Titration] What is my qs?
- [AS Level English: Essay Writing] Should all adverts be factual?
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/r/HomeworkHelp
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[Chem high school] Why is this equation wrong in your honest opinion?
Why do they have 2e?
Ok so on second look, pentane is ionised and so the lost electron joins the electron which caused the ionisation hence 2e. Is that what is being represented by the equatoion?
09:08 UTC
[Grade 11 Physics] Calculate the pressure difference between two ends of a capillary tube
Two capillary tubes AB and BC are joined end to end at B, AB is 16cm long and of diameter 4mm whereas BC is 4cm long and of diameter 2mm. The composite tube is held horizontally with A connected to a vessel of water giving a constant head of 3cm and C is open to the air. Calculate the pressure difference between B and C. (In centimeters of a column of water)
I tried to solve this by solving for the pressure difference between A and B, which is rho * g* h which is 1 * 980 * 3 = 2940 Ba
Then I recalled the equation of continuity
a1V1 = a2V2 a1 = pi * 0.2 ^2 a2 = pi * 0.1^2 V1 = pi/8 * 2940 * 0.2^4/(η*16) V2 = pi/8 * p * 0.1^4/(η*4)
We want to find p/(rho * g) to find the column of water
However when solving for p ( i got 47040) which corresponds to 48 cm of water, but the answer is 2.4 cm How did I go wrong by a factor of 20?
Here is the solution online (which I didn't understand)
09:07 UTC
[Grade 11 Physics] Calculate the pressure difference between two ends of a capillary tube
Two capillary tubes AB and BC are joined end to end at B, AB is 16cm long and of diameter 4mm whereas BC is 4cm long and of diameter 2mm. The composite tube is held horizontally with A connected to a vessel of water giving a constant head of 3cm and C is open to the air. Calculate the pressure difference between B and C. (In centimeters of a column of water)
I tried to solve this by solving for the pressure difference between A and B, which is rho * g* h which is 1 * 980 * 3 = 2940 Ba
Then I recalled the equation of continuity
a1V1 = a2V2 a1 = pi * 0.2 ^2 a2 = pi * 0.1^2 V1 = pi/8 * 2940 * 0.2^4/(η*16) V2 = pi/8 * p * 0.1^4/(η*4)
We want to find p/(rho * g) to find the column of water
However when solving for p ( i got 47040) which corresponds to 48 cm of water, but the answer is 2.4 cm How did I go wrong by a factor of 20?
Here is the solution online (which I didn't understand)
09:07 UTC
[highschool chem] Why is the ion represented with a dot and +
I know that pentane has lost one of a pair of electrons from the electron collision(ionisation) which is represented here
But why do we start with that?
I've got the answer while trying to find the best way to phrase the question
But I have another one, when you play around with the m/z values to see how many carbon atoms a fragment has and finally get a solution, before writing the equation, does that mean whatever breaks away (after getting what you computed based on m/z) becomes the radical, ALWAYS? so that once you have the ion, you can always have the radical
08:47 UTC
[High School Math] How is the answer NOT two zeroes?
After solving the system of equations, the polynomial comes out to be f(x)=x²+1. So from here, it's obvious that the zeroes are x=i or-i. So there are two zeroes. But our teacher is saying that the answer is 0 zeroes..... I have even been marked incorrect in my exam. In an even simpler approach, we know that a nth order polynomiaI has n number of zeroes. So a quadratic equation (as given in question) is a 2nd degree polynomial, so the answer has to be 2 zeroes no matter what right? Even then my answer is incorrect. My teacher is saying "It's 0 because the polynomial does not cut x-axis"but why the hell should I care if it does or not? If it doesn't, it means that there are complex zeroes which are zeroes no matter what. The question doesn't ask for real zeroes so anything goes right? Pls clarify if I have made a mistake somewhere.
08:30 UTC
[Grade 12 Maths: Complex Numbers] Proof
Why do they straight away go for the square of the moduli? How do you know that AB represents a length other than from the first statement of the theorem of 'sum of the square of two sides'?
07:28 UTC
[Grade 12 AP Calc AB finding h’(x) using chain rule]
07:06 UTC
[grade 11] this is confusing
When pentane is hit by an electron and becomes ionised, why does it maintain the same formula even though it has lost an electron? And why is there 2e on the right hand side?
06:50 UTC
[HS Geometry] Is this correct?
06:24 UTC
[Grade 12 Maths: Complex Numbers] -i
-i=cis(-π/2), so
(-i)^(2)=[cis(-π/2)]^(2)=cis(-π)=-1
Is this correct?
What about:
-i^(2)=-[cis(-π/2)]^(2)=-cis(-π)=1
Is the second one true?
What about:
z=-iw
z^(2)=(-iw)^(2)=(-i)^(2)w^(2)=-w^(2)?
Is that true?
04:40 UTC
[Grade 12 Maths: Complex numbers] Argand diagram
Wouldn't it be a kite? So adjacent sides don't have to have equal length?
04:37 UTC
Where did the x^2 in (x^2+1^2) come from? [GRADE 11 PRECALC]
My answer to the problem was ln(sqrt(2x-1) / (x+1)^2). Where did the x^2 in the denominator come from?
03:40 UTC
[HS Geometry] Is this correct?
The problem is, “Plot points F (-2,3), G(-4,0), and H(1,4) on the coordinate plane. Reflect each point through the origin and plot image points. Be sure to label the coordinates of F’, G’, and H’ on the graph.
03:37 UTC
[grade 12 physics right hand rule] right hand rule NEED ANSWERS
03:02 UTC
[Freshman English: book report] best scenes in fresh off the boat?
Hey guys, I have this English project where we have to pick out some important scenes in fresh off the boat: a memoir. Any scenes help, I’m just really blanking. Chapters/Page numbers would also be greatly appreciated!
02:46 UTC
[High school calculus] How should i go about finding the volume? (parts d and h)
02:42 UTC
[University level : Circuits]
So I have tried 2 ways to solve this circuit, did not get the right answer, can someone else help me?
02:38 UTC
[8th Grade Math]
02:12 UTC
[Grade 11 Physics: Mechanics] Circular motion
Is this correct? There's no answers for it so I can't check it
02:07 UTC
[grade 12 chem] Is this hypothetical?
Why does a noble gas have ionic charge? Maybe this was just for demo purposes
01:10 UTC
[Physics 10: Solenoid Diagram]
Hi, could someone make a rough diagram/sketch regarding the question below, as I want to see how it is drawn before attemping my other questions, and I would like someone else's drawing as I am still confused on what to do. Thanks.
Draw a diagram of a solenoid and explain, using field lines, how the magnetic field resembles that of a bar magnet.
00:52 UTC
(senior american gov)
need help ordering the steps in making a bill to a law, tried looking online bit nothing helped at all. thank you in advance!!
00:06 UTC
[chem grade 10-12] I have doubts
- The book doesn't mention how electrons are produced by the heated filament
- How would step 2 even work? the electrons are produced at step 1
- The diagram looks wrong as well
That's from my class notes
I also notice some error in the 2 equations, but would like someone to point it out so I can confirm
Here is EN Ramsden's diagram for comparison:
The problem is that we are required to include the different parts such as vaporisation chamber etc otherwise it would just be easy to follow Ramsden but I may lose marks. What could be the vaporisation chamber in Ramsden's diagram?
The class notes has this chamber as coming before the ionisation stage
00:06 UTC
[Grade 12 Maths: Complex Numbers] Geometry
For a, how do you know the position vectors have twice the lenght of each other? Cause modulus of cisπ/3 is 2? And for b how do you know that the position vectors are all just rotations of 90°?
23:56 UTC
[English 6th grade] find misspelled word
Got 19 of 20 but we cant find the last one
23:47 UTC
[Chem grade 9-12] mistake? supposed to be +
23:29 UTC
[KS3 Maths UK : 11 Plus]
22:43 UTC
[High School Probability] I am getting the answer 1/10 but the answer is 1/8 which is C
21:36 UTC