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  1. C

    Precise definition of the limit (epsilon-delta)

    Sounds like maybe this forum isn't for me then, maybe when I'm better educated. Nothing was taken for granted, thanks to those who did help, I will study your advice and hopefully get it.
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    Precise definition of the limit (epsilon-delta)

    Why is this 4? Is it not 2 or am i seeing this wrong? less than 1? I'm struggling with the, almost, canceling down from factoring to |x-2||x+2|< \epsilon/2 from this step I get really lost, as far as I'm aware the |x-2| is controlled by delta so i have to work with |x+2| by this i use the...
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    Precise definition of the limit (epsilon-delta)

    That's the part I don't truely understand to be honest. The guide I read suggested as your trying to stay witching a small range 1 either side of the value (2) |x+2| is this wrong or have I (the more likely) misunderstood Thanks but I don't quite get your hint
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    Precise definition of the limit (epsilon-delta)

    Not sure if this is right but thought I'd post my progress along with helpful sites in case somebody else has the same problem http://math.stackexchange.com/questions/950493/stuck-on-an-epsilon-delta-proof-where-i-let-delta-be-a-minimum-of-two-values...
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    Precise definition of the limit (epsilon-delta)

    Sorry, I am really struggling with the precise definition of the limit. I have a specific question I'm trying to work out lim(x->2) (4x2+2)=18 skipping the introduction part any advice? I am just not sure how to get rid of the 2 value to re-arrange |(4x2+2)-18| to look like |x-2| |x-2|<delta...
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    Using the precise definition of a limit (epsilon & delta)

    Awh sorry missed that. Yeah it's Lim. (4x^2 +2) = 18 X--> 2
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    Using the precise definition of a limit (epsilon & delta)

    I'm trying to practise, precise definition of a limit (epsilon & delta) Just to check I'm along the right lines here's a previous question to the one I'm stuck on If epsilon > 0 then there is delta >0 ..... All that introduction stuff, then Lim x-> 2 (3x-1) =5 Hence |x-2| < delta then |3x -...
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    Finding the limit 0/0

    Thanks! Much appreciated.
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    Finding the limit 0/0

    Hopefully this will be okay to follow apologies if not, not sure how to write equations on here yet. >> [sqrt(2+2h) - sqrt(2)]/h . [sqrt(2+2h)+sqrt(2)]/sqrt(2+2h)+sqrt(2) >> 2+2h+[sqrt(2)sqrt(2+2h)]-[sqrt(2)sqrt(2+2h)]-2 h.sqrt(2+2h)+sqrt(2) >> cancels to 2h h.[sqrt(2+2h)+sqrt(2)] >> giving, as...
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    Finding the limit 0/0

    I am really struggling with limits at the moment. Any help would be great! Thanks to anyone in advance if they take the time to read the rest of this. Basically i am struggling with finding the limit when using direct substitution provides 0/0 I (think) am fine with limits that involve quadratic...
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    Finding a limit

    Yeah
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    Finding a limit

    That's a much easier way to grasp the concept, thanks! Will get reading! Sorry, I don't suppose you have any advice/similar PDF on the definition of a limit? I feel I'm getting there (although part of me feels it could all be wrong and I'm miles away)
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    Finding a limit

    Thanks! Just clicked into place now, remember him explaining this now. There is some frustrating gaps in my knowledge due to a non traditional route to higher education. Thanks again!
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    Finding a limit

    Apologies if this is in the wrong place. I'm struggling to understand a step in finding a limit Lim(x->0) x.sqrt(x+2) / sin(x) Following the given solution I get to the point where it's all divided through by x to give Sqrt(x+2) / sin x/x Which as approaching 0 gives Sqrt(2) / 1 = sqrt(2)...
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    Energy stored in a capacitor

    Any idea where I've gone wrong?
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    Energy stored in a capacitor

    "calculate the energy stored in the capacitor when the difference of potential between the two plates is 3V" Apologies, yeah i meant CV2/2 but surly that is the same as 1/2 CV2, so using the equation: Capacitance = 1.7 uF = 1.7x10-6 F Difference of potential between the two plates = 3 V //...
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    Energy stored in a capacitor

    Homework Statement Parallel plate capacitor, C = 1.7 uF the difference between the two plates is 3 V Find the energy stored in the capacitor Homework Equations U = 1/2 QV^2 The Attempt at a Solution U = 1/2 (1.7x10^-6 F) (3V)^2 = 3.65x10^-6 J Says the answer is: 1.53x10^-5 J Not sure...
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    Torque about the origin is

    Thanks for all your help, I don't suppose you could reccomend a book/website to learn vectors? I have a physics book by Feynman that has a section on vectors I plan to read. Or would I get a better understanding of vectors from a mathematical viewpoint?
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    Torque about the origin is

    Thanks a lot! yeah, I'm going to spend some much needed time on vectors. I'm not sure how i go about finding the direction as in questions like this?
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    Torque about the origin is

    F(i x j) + 2F(j x j) = Fk + 0 = (1.5k) Nm = 1.5 Nm
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    Torque about the origin is

    sorry you've lost me, how does that let me work out the torque in Nm? I have the possible answers -4.5, 4.5, 1.5, 3, 0
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    Torque about the origin is

    I'm assuming its the k component, that's the vertical part of i,j,k, right? Thanks for the reply, i just seem to be struggling understanding the question to be honest. If it is the k component then surely the cross product would give 0 as well?
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    Torque about the origin is

    Homework Statement a point particle is located in the position r=i+2j m . A gravitation (vertical) force of 1.5N acts on the particle. The torque about the origin is... Homework Equations thau = r X F = rFsin(theta) The Attempt at a Solution it's 0 right? magnitude r = sqrt(1^2+2^2)m...
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    How the speed of particles is affected

    So to see the relationship between the particles and the speed of the container, you could use the following? 3/2 RT (=KE of gas molecules) + 1/2 mv2 (container) but this doesn't obey, PV = nRT or P = T If there is not a change in pressure, this will = no change in temperature but how can there...
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    How the speed of particles is affected

    That's great, thanks, its given me a better understanding. Sorry my question wasn't to clear, I guess I'm trying to understand the relationship between the speed of the container and the particles speed & energy. Is there an equation to show the relationship? would the SUVAT equations be used?
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    How the speed of particles is affected

    Sorry last question, but even if their bulk velocity doesn't affect the relative. if the container is moving at a speed, when the particles collide with the surface of the container would this not affect the speed? so would the KE gained not affect the energy needed for a successful collision...
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    How the speed of particles is affected

    Thanks haruspex, I have a little confusion over whether the increase in KE would affect the particle collisions? Thanks for your time
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    How the speed of particles is affected

    Apologies if this isn't the right place but I saw a moderators post saying all questions should be posted in this section. My physics knowledge is at a general A-level standard at the moment, I was curious about something and was just wondering if someone could help me find an answer. My...
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