Exercise Definition and 578 Threads

  1. Basti3018

    Bonding and Deformation exercise

    Homework Statement A Titanium alloy hast he following mechanical properties: ultimate tensile strength = 860 MPa, yield stress = 780 MPa, maximum strain = 15%, Young’s Modulus E = 120 000 MPa, density ρ = 4,5 g/cm3. To what percentage can the material be deformed elastically? Plastically? How...
  2. L

    Python Beginner coding exercise confusion

    #mark contains personal comments and thoughts # BTW this assignment was a beginner exercise at codeacademy intended to test the usage of if-structures # I was wondering about whether or not if-structure was going to work, or if I needed a loop-structure becauses I wanted to interrogate the...
  3. caffeinemachine

    MHB Stein-Shakarchi 'Complex Analysis' Chapter 3 Exercise 15 b.

    I am stuck on a problem given in Stein and Shakarchi's Complex Analysis. (Chapter 3, Exercise 15b) Use the maximum modulus principle or Cauchy inequalities to solve the following: Let $f$ be a bounded holomorphic function on the open unit disc, and suppose that $f$ converges uniformly to $0$ in...
  4. Kernul

    Exercise counter-image with two variables

    Homework Statement I have this linear application: ##f : \mathbb {R}^4 \rightarrow \mathbb {R}^4## ##f((x, y, z, t)) = (-2x - y + t, 2x + y - t, -4x - 2y + 2t, 0)## and then I have this vector which I have to find the counter-image of it: ##\vec v = (-k, h - 2, k, h^2 - 4)## With ##h## and...
  5. R

    Exercise on adding elements to a list

    (mentor note: moved here from another forum hence no template) This is the code with also the explanation of the exercise. There is bit of italian, but everything is clear enough. I actually solved the exercise. /* Add an element of value n before each element of the list that satisfies the...
  6. M

    How to Find Ψ(x,t) for a Given Hamiltonian Matrix and Initial State?

    Homework Statement I have the matrix form of the Hamiltonian: H = ( 1 2-i 2+i 3) If in the t=0, system is in the state a = (1 0)T, what is Ψ(x,t)? Homework Equations Eigenvalue equation The Attempt at a Solution So, I have diagonalized given matrix and got...
  7. Math Amateur

    MHB Maximal Ideals - Exercise 5.1 (iii) Rotman AMA

    I am reading Joseph J. Rotman's book: Advanced Modern Algebra (AMA) and I am currently focused on Section 5.1 Prime Ideals and Maximal Ideals ... I need some help with Exercise 5.1, Part (iii) ... ...Exercise 5.1 reads as follows: Can someone please help me to get a start on this exercise...
  8. Math Amateur

    MHB Maximal Ideals - Exercise 5.1 (ii) Rotman AMA

    I am reading Joseph J. Rotman's book: Advanced Modern Algebra (AMA) and I am currently focused on Section 5.1 Prime Ideals and Maximal Ideals ... I need some help with Exercise 5.1, Part (ii) ... ...Exercise 5.1 reads as follows: Can someone please help me to get a start on this exercise...
  9. Wolfrider

    Traction/ Compression stress and strain exercise

    Hello everyone, could you help me with this exercise? I am stuck, and I can't find anything on the internet that solves this. Your help is very much appreciated :) 1. Homework Statement Circular steel bar, clamped at extremities. Two parts: A(ab)=800mm² A(bc)=400mm² L(ab)=...
  10. gasar8

    Introductory Quantum Mechanics exercise.

    Homework Statement We describe particle's movement with the Hamiltonian: H=- \frac{\Delta E}{2} |0\rangle \langle0| + \frac{\Delta E}{2} |1\rangle \langle1|, where |0\rangle and |1\rangle are the ortonormal basis. Let: |a\rangle = \frac{1}{\sqrt{2}}|0\rangle +\frac{i}{\sqrt{2}}...
  11. W

    Bernoulli equation exercise from Fanning and Moody

    Homework Statement I would really appreciate it if you could give me a hand with this exercise, not sure on what I've done. Data: Moody: L=55*10-3m D=10-1m k=0.0002m Homework Equations ##Re=\frac{D*u*ρ} {μ}## ##Re=\frac{4*m} {pi*D*μ}## Relative roughness ##ξ=\frac k D## where k=rougness...
  12. W

    Calculating Heat Transfer in a Tube and Shell Exercise

    Homework Statement Would really appreciate if you could lend me a hand with this tube and shell exercise.[/B] m=0.24kg/s ##D=2.5*10-2m## ρ=850 kg/m^3 cp=2000 J/kg*K μ=2*10-4 kg/m*s λ=0.3W/m*k Homework Equations Dittus-Boelter:Nu=0.023*Re0.8*Prn where n=0.4 heating and n=0.3 for cooling, so in...
  13. W

    Approaching Heat Transfer TNT Exercise Using Log-Log Plots

    Homework Statement I would really appreciate if you could give me some hints regarding what exactly to do at iv)[/B] iv) Given formulas: Homework Equations f(y)=(ro*R^5/E*t^2) The Attempt at a Solution we know that f(y)=0.75 1ton TNT=4.184*10^9 J ro=1.003kg/m^3 We have the above...
  14. W

    Parallel Flow Exercise Homework: Find QB Value

    Homework Statement I would really appreciate if you could give me some hints regarding what exactly to iii) Homework Equations we know they are in parallel so Q=Q1+Q2+...+Qn delta hloss=delta hloss1+deltahloss2+... delta P=delta P1=delta P2=...The Attempt at a Solution We know flow is...
  15. berkeman

    Exercise ball "chair" for work desk....

    Have there been any studies looking at the ergonomics of using an exercise ball as your work desk chair? I have a close friend with lower back and leg pain who is looking for ergonomics options. There are lots of studies about keyboard positions, etc. EDIT -- She is also talking to her doctor...
  16. Math Amateur

    MHB Projective Algebraic Geometry - Exercise 6 in Section 8.1, Cox et al

    I am reading the undergraduate introduction to algebraic geometry entitled "Ideals, Varieties and Algorithms: An introduction to Computational Algebraic Geometry and Commutative Algebra (Third Edition) by David Cox, John Little and Donal O'Shea ... ... I am currently focused...
  17. Math Amateur

    Projective Plane - Cox et al - Section 8.1, Exercise 4(a)

    Homework Statement I am reading the undergraduate introduction to algebraic geometry entitled "Ideals, Varieties and Algorithms: An introduction to Computational Algebraic Geometry and Commutative Algebra (Third Edition) by David Cox, John Little and Donal O'Shea ... ... I am currently...
  18. Math Amateur

    MHB Projective Algebraic Geometry - Exercise 4(a) Cox et al - Section 8.1

    I am reading the undergraduate introduction to algebraic geometry entitled "Ideals, Varieties and Algorithms: An introduction to Computational Algebraic Geometry and Commutative Algebra (Third Edition) by David Cox, John Little and Donal O'Shea ... ... I am currently focused on...
  19. Math Amateur

    MHB Help with Exercise 3(c) in Cox et al's Projective Algebraic Geometry

    I am reading the undergraduate introduction to algebraic geometry entitled "Ideals, Varieties and Algorithms: An introduction to Computational Algebraic Geometry and Commutative Algebra (Third Edition) by David Cox, John Little and Donal O'Shea ... ... I am currently focused on...
  20. Math Amateur

    MHB Peter Needs Help on Cox et al - Section 8.1, Exercise 3(a)

    I am reading the undergraduate introduction to algebraic geometry entitled "Ideals, Varieties and Algorithms: An introduction to Computational Algebraic Geometry and Commutative Algebra (Third Edition) by David Cox, John Little and Donal O'Shea ... ... I am currently focused on Chapter...
  21. D

    Partial fraction decomposition exercise 2

    Homework Statement Hello! Here is my second post on the subject partial fraction decomposition. The subject looks pretty easy to learn, but when I try exercises, I do not get to the correct answer. Please, take a look at the exercise below and help me to see my mistakes. Homework Equations...
  22. Kernul

    Synchronous Counter Mod-12 Up/Down Exercise

    Homework Statement "Design a Synchronous Counter Mod-12 Up/Down, using only Flip-Flop Type D. A binary input ##U## that determines if the counter has to increase (##U = 1##) or decrease (##U = 0##). Homework Equations Flip-Flop Type D equation is ##Q_{t + 1} = D## The Attempt at a Solution I...
  23. S

    Exercise about the wavefunction

    Homework Statement [/B] Consider an ideal rope where there is a wave moving at velocity ##v=20 m/s##. The displacement of one end of the rope is given by $$s(t)=0.1 \mathrm{sin}(6 t)$$ a) Find the wavefunction ##\xi(x,t)##, knowing that it is progressive b) Find the distance ##\delta## (in...
  24. tasos

    Pion's mean free path in a lake. exercIse question

    Homework Statement Charged pion with average life time $$\tau=10^{-8} sec$$, and mean free path in the water$$\ell=100m$$ falls prependicular to a lake (depth of lake is at $$\ell_0 =30m$$ with velocity $$V=0.9999c$$ What of the next is correct? 1). The particle isn't gona touch the bottom of...
  25. Rampart

    Conditional Probability exercise with dice

    Hey there community, I have a question on an exercise. Actually it is a general question based on it. Here is the exercise: We throw 3 dice. If we know that the sum of these 3 is 10, then what is the probability of at least one of them being 3? Well now, this exercise is very simple. I mean I...
  26. Kernul

    Exercise with intersection and sum

    My professor did this exercise that I didn't quite get how she went through all of it. We have a ##U = {(x, y, z, t) : x+y+z+t = 0}## and ##B_{Im(f)} = \left[ \begin{pmatrix} 7 \\ -3 \\ 0 \\ 0 \end{pmatrix}, \begin{pmatrix} 3 \\ -3 \\ 0 \\ 0 \end{pmatrix}, \begin{pmatrix} 5 \\ 0 \\ 1 \\ -5...
  27. Kernul

    Exercise with a total charge null

    Homework Statement A point charge ##q = 30 mC## is located in the center of a conductor spherical shell with an internal radius of ##a = 10 cm## and an external radius of ##b = 20 cm## and total charge null. Find the surface density charge of both the internal surface and external surface of...
  28. Frankenstein19

    Why is acceleration positive in this exercise?

    Homework Statement Calculate the acceleration of a 1400kg car if it can stop from 35km/h (9.72m/s) on a dime (diameter= 1.7cm) (0.017m). What is the force felt by the 68kg occupant of the car? Homework Equations v^2=v0^2+2a(x-x0) F=ma The Attempt at a Solution ok after solving for a in that...
  29. D

    What Is the Correct Theoretical Yield of HNO3 in This Chemistry Problem?

    Homework Statement Hello! I would be grateful for your help on finding my mistake - somehow my answers are wrong compared to the answer from the book. Here is the exercise from a paragraph on gases (cumulative gas law, basics): Consider the reaction for the synthesis of nitric acid: 3NO2 + H2O...
  30. Shadow-Shocker

    LabView Weather Station Exercise problem

    I am doing a Weather Data Log exercise, and I am looking for the program to run continuously. However, every time I run it, the program would always direct me to store the data in a file for every run I do. Please look at the following pic. Btw, I am running this on a Mac, using parallel's...
  31. Kernul

    Calculating Electric Potential in a Series of Capacitors

    Homework Statement Three capacitors ##C_a = C, C_b = 2C, C_c = 3C## are positioned like in the figure. The A capacitor's electrode has a ##V_a = 20 V##, while the B capacitor's electrode has a ##V_b = 80 V##. What is the electric potential ##V_3## of the C capacitor's electrode? Homework...
  32. hubot

    Feynman exercise - container with steel balls

    Homework Statement You received many steel balls of the same diameter d and container of known volume V. All dimensions of the container are much greater than balls diameter. How many balls can be placed in a container? Homework Equations (\frac{4}{3}\pi)(\frac{d^3}{8})\approx0,52d^3 The...
  33. Doney Felipe MEjia

    Can someone help me with an analytical dynamics exercise?

    At a certain instant, the velocity and acceleration of a particle ar defined by v= 3i + 4j - 6k m/s and a=-2i + 3k m/s2. Find the radius of curvature and change of speed of the particle at the instant.
  34. MathematicalPhysicist

    Exercise 26 in Schutz's First course in GR

    Homework Statement The question as follows: Calculate the energy that is required to accelerate a particle of rest mass ##m\ne 0## from speed ##v## to speed ##v+\delta v## (##\delta v \ll v##). Show that it would take an infinite amount of energy to accelerate the particle to the speed of...
  35. I

    MHB Not an exercise, more of a question.

    If I have a number n and I want to know all the unique ways in which I can use u addends to get that number... How do I do it? For example: If the number is 6 and I want to see how many unique ways I can add up to it (order matters: 1 + 1 + 2 + 2\ne 2 + 2 + 1 + 1) by using 4 addends, what's...
  36. Kernul

    Law of Conservation of Mechanical Energy Exercise

    Homework Statement A mass ##m_1 = 5.0 kg## is hanging from the end of a thread, of negligible mass, that slides on a pulley, of negligible mass too and without friction. At the other end of the thread, at the same height of ##m_1##, there is another hanging mass ##m_2 = 3.5 kg##. Using the Law...
  37. Velo

    MHB Logarithm + Nepper's number Exercise

    " Solve the equation: 2e^(-x) = 3e^(0.1x) " I've been fiddling around with this and I have no idea what I'm supposed to do. I know the final answer should be something like: x = [(2/3)log e] / 1,1 The only step I've managed to do was: (2/3) x e^(-x) = e^(0.1x) But after that, I don't know...
  38. Kernul

    Exercise with Linear Transformation

    Homework Statement Being ##f : \mathbb R^4\rightarrow\mathbb R^4## the endomorphism defined by: $$f((x,y,z,t)) = (13x + y - 2z + 3t, 10y, 9z + 6t, 6z + 4t)$$ 1) Determine the basis and dimension of ##Ker(f)## and ##Im(f)##. Complete the base chosen in ##Ker(f)## into a base of ##\mathbb R^4##...
  39. RGalbiati

    Quantum Quantum mechanics (mathematics): exercise book

    Hi everybody I'm currently looking for an introductory quantum mechanics book which emphasizes the mathematical aspects of it. I especially need exercises in order to pass a written exam, but I'd like to have even lots of examples. I've already gone through the whole "Picasso" (it's an italian...
  40. D

    Exercise about determining energy of light that breaks bonds

    Homework Statement Hello! Here is the quote of the exercise: Excessive exposure to sunlight increases the risk of skin cancer because some of the photons have enough energy to break chemical bonds in biological molecules. These bonds require approximately 250–800 kJ / mol of energy to break...
  41. Kernul

    Exercise: position vector of a particle

    Homework Statement The acceleration of a particle moving only on a horizontal xy plane is given by a = 3ti + 4tj, where a is in meters per second squared and t is in seconds. At t = 0, the position vector r = (20.0 m)i + (40.0 m)j locates the particle, which then has the velocity vector v =...
  42. Math Amateur

    MHB Basic Exercise in Vector Spaces - Cooperstein Exercise 2, page 14

    I am reading Bruce Cooperstein's book: Advanced Linear Algebra ... ... I am focused on Section 1.3 Vector Spaces over an Arbitrary Field ... I need help with Exercise 2 of Section 1.3 ... Exercise 2 reads as follows:Hope someone can help with this exercise ... Peter*** EDIT *** To give...
  43. Math Amateur

    MHB Basic equation in Vector Space - Cooperstein Exercise 1, Section 1.3

    I am reading Bruce Cooperstein's book: Advanced Linear Algebra ... ... I am focused on Section 1.3 Vector Spaces over an Arbitrary Field ... I need help with Exercise 1 of Section 1.3 ... Exercise 1 reads as follows:Although apparently simple, I cannot solve this one and would appreciate...
  44. D

    What is the height of the parabolic arch at a point 1 foot in from the base?

    Homework Statement Hello! Please, take a look at this exercise. A parabolic arch is constructed which is 6 feet wide at the base and 9 feet tall in the middle. Find the height of the arch exactly 1 foot in from the base of the arch. I have trouble solving it. Please, guide towards a correct...
  45. Math Amateur

    MHB Vector Spaces - The Space F^n - Cooperstein Exercise 12, page 10

    I am reading Bruce Cooperstein's book: Advanced Linear Algebra ... ... I am focused on Section 1.2 The Space \mathbb{F}^n ... I need help with Exercise 12 ... since I do not get the same answer as the author ... Exercise 12 reads as follows: My attempt at a solution to this apparently...
  46. Math Amateur

    MHB Sums and Intersections of Submodules .... Berrick and Keating Exercise 1.2.12

    I am reading An Introduction to Rings and Modules With K-Theory in View by A.J. Berrick and M.E. Keating (B&K). I need help with Exercise 1.2.12 ... Exercise 1.2.12 reads as follows: https://www.physicsforums.com/attachments/5102 Can someone please help me to get started on this problem ...
  47. Math Amateur

    MHB C[T] modules - Berrick and Keating Exercise 1.2.8 (c)

    I am reading An Introduction to Rings and Modules With K-Theory in View by A.J. Berrick and M.E. Keating (B&K). I need help with Exercise 1.2.8 (c) ... Exercise 1.2.8 (c) reads as follows:Now ... from this exercise we have that M \equiv \mathbb{C}^3 ... and ... A = \begin{pmatrix} 0&1&1 \\...
  48. O

    Finding i(t) in a Circuit with Phasors: Introductory Exercise

    Homework Statement In this circuit, find i(t), knowing that v_s= 2 \cos \left(w x+\frac{\pi }{2}\right), and that, at the source's frequency, X_C= -1 Ω and X_L = 1 Ω. Homework Equations Basic phasors and dividers equations. Z_C = jX_C Z_L = jX_L The Attempt at a Solution I used dividers...
  49. King_Silver

    Exercise Question from Maths book

    Homework Statement "Find all the points on the curve with equation 6y = 2x^3 + 3x^2 + 6x + 5 where the tangent is parallel to the line with equation 3x − y + 2 = 0 Homework Equations No idea The Attempt at a Solution There are no exercises in the book even similar to this example which is...
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