problem Definition and 40 Threads

  1. I

    Lattice point problem from Stewart's Calculus

    So, the way I understand this problem, I think the line ##y = (2/5)x + c## should only intersect some of the circles drawn around the lattice points. But, I am not sure I even understand the problem statement. Can the line pass through the lattice points ? My first goal is to understand the...
  2. chwala

    Solve the given problem involving integration

    This really cracked me up! Unless there is something i am not seeing! part (a) is straightforward, using quotient rule: ##\dfrac{dy}{dx} = \dfrac{x⋅\dfrac{1}{x}- \ln x}{x^2}=\dfrac{1-\ln x}{x^2}## From here i was able to see that, ##\int \dfrac{\ln x}{x^2} dx= \int \dfrac{1}{x^2}- \dfrac{\ln...
  3. L

    Can square roots be simplified without a calculator?

    I can't find a short solution without using calculator.
  4. L

    Proving a statement about covered intervals

    I need any idea. I haven't made any progress in solving the problem.
  5. Heisenberg7

    Studying Advice for How to Attack Problems

    Hello, I was lying in bed the other day and an idea came to my mind. How does one actually solve a problem? Now, I know this question is impossible to answer, but I would like to know your strategies when it comes to solving problems. I would like to make an analogy to this. Let's say that you...
  6. M

    Understanding the solution to this subspace problem in linear algebra

    For this problem, The solution for (a) is I am slightly confused for ##p \in W## since I get ##a_3 = 2a_1## and ##a_2 = 2a_0##. Since ##a_3 = 2b##, ##a_2 = 2a##, ##a_1 = b##, ##a_0 = a##. Anybody have this doubt too? Kind wishes
  7. tellmesomething

    What am I doing wrong while solving problems?

    This site probably gets similar questions all the time, apologies if its too repetitive. I know the ultimate answer is to keep practicing, anything else is just a way of procrastination (including this post) but I feel like im doing something wrong somewhere. I'll explain this with an example...
  8. N

    Find the Period of Oscillation for a Mass Falling Through a Tunnel Through the Earth

    I'm trying to solve it by 2 methods(screenshot below). However, I'm getting 2 different answers. I'm not able to find out the error in method 1. Method 2 gives the answer correctly. Kindly help. P. S: If the pics are not clearly visible enough, kindly let me know. I'll try to either improve the...
  9. N

    Block and wedge problem -- Where am I going wrong?

    This question is from the book Kleppner and Kolenkow Q 3.8: ___________________________________ My attempt is posted here: ___________________________________ The value of a(minimum) that I'm getting is different from the official solution. The official solution is posted here...
  10. chwala

    Solve the given trigonometry problem

    My question is on the highlighted part (circled in red); Why is it wrong to pre-multiply each term by ##e^x##? to realize , ##5e^{2x} -2-9e^x=0## as opposed to factorising by ##e^{-x} ## ? The other steps to required solution ##x=\ln 2## is quite clear and straightforward to me.
  11. chwala

    Find ##\tan \theta ## in the form of ##a+b\sqrt {2}##

    There is an error on ms ...unless i am missing something.
  12. Florian Geyer

    Other A problem in my transcript

    Hello esteemed members I hope this message finds you all well. I am writing to you to address what I think are inaccuracies in my English transcript of the courses I have studied in my university, which is my courses’ titles are not correct. For example, "General Mathematics 1" should actually...
  13. Owen Ploe

    HI!

    I was looking for videos, or post on how to do a physics home work problem. Ended up finding a similar post on this website. It didn't quite answer my question, but I thought I could post here to figure it out.
  14. D

    I Post your favorite real analysis problem

    I figure one can dig around for plenty of quality problems online, but I'm hoping to skip right to the good stuff by you posting your favorite real analysis problems from college, internet, textbook, dream, imagination, etc. It would be so helpful to get some comments this time, and please don't...
  15. gmax137

    Necroposts

    Is necroposting seen as a problem here on PF? Screenshot below from another forum shows an approach to avoiding necroposts, at least those unintentional ones.
  16. chwala

    Solve the given word problem: Selecting 2 numbers from a watch face

    I honestly do not understand this question, my thoughts; ignoring the diagram and using algebra i can see that the step size [1,5] → [2,6] can be found by adding 1 (common difference) to each number meaning that the answer is A... ...the other options B,C,D and E can not be related by a...
  17. krissturm

    Flow discharge between 2 open water bodies connected by a concrete sluice

    Hello, Looking for help with a physics problem. I am dealing with a problem regarding the flow discharge between 2 open water bodies connected by a concrete sluice with gates. The issue is that the channel is not straight but rather a trapezoid (image of the cross-section below). The discharge...
  18. elou

    I Feynman discussion of electron diffraction

    Feynman, in the third volume of his Lectures on Physics, chapter 1, presents bullets and waves in two different diagrams, Fig 1-1 and 1-2 respectively. https://www.feynmanlectures.caltech.edu/III_01.html It is obvious that bullets are counted individually, the detector registering each hit...
  19. Chestermiller

    I Interesting Thermodynamics Problem deleted in PhysicsStackExchange

    I came across this very interesting Thermodynamics problem in PhysicsStackExchange. It was deleted by the OP because the moderators, in their infinite wisdom, gave him a hard time about its being a homework problem which was, in their opinion, a "check my work" post, rather than a "I'm having...
  20. ashley2024

    How Do You Solve a Non-Equilibrium Pulley System with a 154 Degree Angle?

    Please note that the system is not in equilibrium, and that tension must be solved for the instant where the angle is 154 degrees. My attempt (correct ans is Ft = 626N)
  21. Marina123456

    How can I fix the illegal data signal error in my FMESH tally code in MCNP6?

    Hi everyone, I would help in such problem. i have tried to use a fresh card, but it always gives an illegal data signal am using mcnp6. here is my fmesh code. thanks FMESH44:n GEOM=X Y Z ORIGIN=-10 -10 -10 IMESH=-50 IINTS=5 JMESH=50 JINTS=11 KMESH=50 KINTS=8 EMESH= 1e-7...
  22. S

    Create a physics problem for me!

    Hello! Using concepts of physics 1 like kinamatics, dynamics, circular motion, pressure, newton's laws. Make me a physics question that needs basic calculus like integrals and derivaties to solve!
  23. paulb203

    Basic Simultaneous Equations Problem

    I got c=13, but I'm using an app that, at the 'diagnostic' stage, doesn't tell you if you're correct or not (I multiplied the first equation by 4, and the second by 2, then subtracted the second from the first)
  24. Ineedhelpwithphysics

    Two dimensional motion problem (kicking a soccer ball into the goal)

    I did this too fast idk if I'm wrong So for the x component use the formula d = rt / delta x = v*t 26 = vcos(theta) y component use the displacement formula 19.6 = vsin(theta) tan^-1(19.6/26) = 36.5 degrees the answer key says 20.2 degrees idk whats wrong
  25. M

    I Work done in cycle of a refrigerator (in Heat and Thermodynamics by Zemansky)

    I guess the first one is wrong. Because in this cycle we have ##|Q_H| > |Q_L|## then ## |Q_L| - |Q_H| ## is negative and caanot be equal with ##|W|##. Am I right?
  26. torinketo

    Why Do I Get Negative Values Solving the SHM Spring Problem?

    m1 = unknown m2 = 0.05 kg x = 0.38 m T = 0.8s Tried to plug in values into the above equations: 0.8 = 2pi*sqrt(m1+0.05/k) k = ((m1+0.05)*9.8)/0.38 Got negative values for both k and m which doesn't make sense
  27. damanr

    Indentations in the contact surface of the clutch drum and the circula

    Hello guys, in my work we have a problem detected in the clutch drum (automatic gearbox) : indentations in the contact of the clutch drum and the circular plate, wefound that the hardness of the circular plate is higher than the clutch drum, do you guys have some propositions to solve this?
  28. R

    Challenge: Find the minimum amount of draws possible for a list of integers

    Hello. Sorry if the title is a bit vague. I'm doing this challenge (google foobar) and even though it's not very elegant to ask for help, it's not like I'm going to win any kind of prize for it. In any case I'd like some suggestions since my current solution fails 2 tests on 5. The most...
  29. JMAMA

    Newton's law problem: Pushing 2 stacked blocks on a horizontal table

    Would anyone be able to help with this Newtons law problem Block A rests on top of block B as shown in (Figure 1). The table is frictionless but there is friction (a horizontal force) between blocks A and B. Block B has mass 6.00 kg and block A has mass 2.00 kg. If the horizontal pull applied to...
  30. chwala

    Solve the problem that involves diameter of the Bullseye

    I really do not understand what they are asking here...wording here in english is a bit confusing to me...but from similar examples, i made use of the approach below (which i still do not understand) hence my post. ##\dfrac{30π}{60 ×180} = \dfrac{0.0254}{d}## ##d = \dfrac{274.32}{30π}## ##d=...
  31. A

    I need feedback on MCQ test in IJSO style

    Solutions are also attached as a file
  32. Lotto

    Running princess and spider - time problem

    If the veil stretches prefectly, then when the princess moves by ##\Delta x##, then if the spider was not moving, he would also move by ##\Delta x## from the door, so he would be in the same distance from the princess. So assuming it, the time would be ##t_f=\frac {l_0}{u}## but that is no...
  33. phinds

    Problem with FireFox browser (BUT, it turns out, not with PF)

    I get PF to work just fine with Chrome and Edge but it's a mess with Firefox. I've cleared the cache, closed Firefox and opened it again. No joy. Anyone else using Firefox here and NOT having problems? Also, FYI, I'm using Windows 10 and Firefox says I have the latest version
  34. chwala

    I Solve the problem involving Rings

    Its a bit clear; i can follow just to pick another polynomial say ##(x+1)^3## are we then going to have ##(2x-2)+ x+3##? or it has to be a polynomial with ##x^2+1## being evident? cheers...
  35. niko_niko

    Confusion on mechanics problem involving cart, blocks, and pulley

    [Mentor Note -- Two threads on the same by the OP have been merged into one] I'm having trouble understanding the solution my professor gave me, in particular, the accelerations of m_2 and m_1. When my professor solved for the acceleration of m_2, he used a as the acceleration but when I look...
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