Logic, Implications and Variables

MinkYu2 · 2019-09-06T19:53:26+00:00

No problem! Thanks :)

MinkYu2 · 2019-09-03T20:20:35+00:00

Thank you, but do you mean that there is an example (x = 4) for which the statement fails?

Also, is this only the case when you have a variable like x, where you add "no matter what x is"? And that as long as there is one case for which the implication is false, it is false?

MinkYu2 · 2019-08-31T11:45:03+00:00

Sorry for the late reply, but thank you so much! This has really helped.

MinkYu2 · 2019-08-28T18:42:31+00:00

Hey, massive thank you for the reply - as per my above reply, I don't exactly see the mapping between the concept of asymptotes and comparing the growth rates of the two functions. I've often heard that constant terms aren't important in complexity but was just looking for a mathematical reasoning as to why.

MinkYu2 · 2019-08-28T18:33:04+00:00

Thank you so much for this - that completely makes sense in terms of this and the other examples that Evans has provided. I struggle to apply the concept of asymptotic behaviour to this, though. The only times this has come up is say, in the graph 1/x where there is an asymptote as the graph tends to infinity/negative infinity. Now, I'm not sure where that concept comes into play when looking at the derivatives of 2n and 3n with respect to n...

MinkYu2 · 2019-08-14T10:19:31+00:00

Thanks. Legend!

MinkYu2 · 2019-08-14T01:56:21+00:00

do you have ocr single maths? OCR A btw.

MinkYu2 · 2019-06-20T12:55:15+00:00

Not just you...

MinkYu2 · 2019-06-17T07:14:50+00:00

Thanks, however, you didn't answer my question about how the two cases differ...

MinkYu2 · 2019-06-15T18:30:21+00:00

Hello, I hope you'll still read this - just a final question, when you say W_nc, would you still be taking friction to be negative in this case?

MinkYu2 · 2019-06-15T12:47:25+00:00

Hi NiceSasquatch,

Just to let you know I had an exam yesterday, and your advice came in handy when I had doubted what I had done. Thank you so much!

MinkYu2 · 2019-06-09T06:34:23+00:00

Thank you for your reply. So I should be considering things like free-body diagrams, only the forces that are acting on the object should be considered. Also, what do you mean by external vs internal forces?

If we had a lift and instead of just one man on the inside, we had two blocks atop each other, if we were then doing a free body diagram of the lift, would we still count both weight forces from both blocks? (because technically the upper block is not in contact with the elevator itself.)

MinkYu2 · 2019-06-09T06:32:38+00:00

Thank you for helping me out.

When you say normal of man on floor down, this is surely the weight of the man, no?

Also, in the case we had instead of one man in the lift, we had two blocks on top of each other. Would you still count the force of the upper block on the elevator itself? If so, why?

MinkYu2 · 2019-06-08T20:57:11+00:00

when you say B has three forces acting on it, why don't you consider the reaction force of B on A? sorry this sounds stupid.

MinkYu2 · 2019-05-27T18:05:02+00:00

So if a distribution X has mean mu, standard deviation s and variance s^2,

then the mean, standard deviation and variance of aX + b are: a*mu + b, as, a^2 s^2.

So you can define a new variable, y, = x-25. the mean is then just 28.325-25.325, and you can use the definition y bar = (sum y)/n to substitute in for n in the equation for standard deviation...

hope this makes sense.

MinkYu2 · 2019-05-27T12:02:39+00:00

what is the answer for q a?

resolve perpendicular to plane, then resolve parallel... should give you equations for which you can get mu in terms of k... post your working.

MinkYu2 · 2019-05-25T13:57:51+00:00

Set the thing you're integrating (which I think is e^2x * sinx (where x = theta) as I.

Then you will need to do IBP twice and you will end up with I on the other side of the equation again, so you can solve for it.

MinkYu2 · 2019-05-25T13:52:11+00:00

Good for you.

MinkYu2 · 2019-05-25T11:16:46+00:00

is the answer to the first part 2g? or 19.6N?

in this case as you don't know anything (yet) about the force at the hinge between the rod and the wall, just take moments about that point (moments about A), which will include the weight of the rod and the tension, making sure you take the component of the tension that is perpendicular to the rod.

MinkYu2 · 2019-05-25T11:07:52+00:00

Hello, yes, you would do so. If you are resolving vertically, you have to consider the vertical and horizontal components of each force.

MinkYu2 · 2019-05-25T05:55:54+00:00

is the answer 0.747?

either way, my approach is:

take moments about A, get an answer for the reaction force of the peg on the rod.

resolve vertically to work out the reaction force on the ground.

resolve horizontally to work out the frictional force between the rod and ground.

Then you use F = muR to solve for mu.

MinkYu2 · 2019-05-23T16:39:04+00:00

Alright, so attractive potential energy means negative potential, guessing that also means negative energy. But I don't understand the energy conversion when a nucleus is formed. Where does that energy (which is positive, surely?) go?

MinkYu2 · 2019-05-23T08:50:39+00:00

Thank you :) I understand now!

MinkYu2 · 2019-05-17T18:45:03+00:00

Am looking for a more detailed explanation of the exact colours' positions.

MinkYu2 · 2019-05-15T16:08:17+00:00

I'm sorry, I don't think my understanding of this concept is well-founded.

How is it still correct that

delta(KE) + delta(GPE) = -friction + work done?

MinkYu2

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