What is Difficulty: Definition and 268 Discussions

Degree of difficulty (DD, sometimes called tariff or grade) is a concept used in several sports and other competitions to indicate the technical difficulty of a skill, performance, or course, often as a factor in scoring. Sports which incorporate a degree of difficulty in scoring include bouldering, cross-country skiing, diving, equestrianism, figure skating, freestyle skiing, gymnastics, rhythmic gymnastics, surfing, synchronized swimming and trampoline. Degree of difficulty is typically intended to be an objective measure, in sports whose scoring may also rely on subjective judgments of performance.

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  1. T

    Difficulty with orbital period

    Homework Statement Find the speed of an Earth satellite whose orbit is 400km above the Earth's surface. What is the period of the orbit. Homework Equations The first part was pretty easy. I used v=[(Gm)/r]^(1/2) to get the answer. The Attempt at a Solution For the first part, I...
  2. T

    Significant Figures difficulty

    Homework Statement A newspaper reported an attendance of 15,000. If you assume that this number contains two significant figures, how many people could actually have been at the game? The Attempt at a Solution I'm having difficulty answering this problem not because I don't know how to...
  3. M

    Why Can't I Get Audio for Quake on My Vista Computer with DosBox?

    Why can't I get audio for "Quake"?
  4. A

    Edwin Spanier Algebraic Topology difficulty?

    How difficult is Spanier's Algebraic Topology text to understand? How about the exercises?
  5. N

    Difficulty of upper level physics

    I am physics major and just started taking my upper level physics course at the beginning of the fall semester. Obviously, the jump in difficulty from freshmen level physics is quite large, as I expected. However, on exams, many of the questions expect us to conjure up clever manipulations, or...
  6. S

    DC to AC Inverter Design Difficulty

    Hey Guys, I'm having trouble designing an inverter to power an ac motor using a fuel cell with MATLAB. With the inverter, the output current of the DC converter dips below 0 and the fuel cell does not like that at all because it causes a 'ln of -ve number' error. I have tried placing an...
  7. F

    I underestimated the difficulty of Widder's Advanced Calculus

    I somehow managed to get Bs in two calculus courses and was pretty confident that in a pinch I was capable of doing work involving lagrange multipliers, Green's theorem, convergences of improper integrals, and such. My textbook was multivariable calculus by Larson and Edwards which I was sold...
  8. M

    Climbing the Mathematical Ladder: Understanding Difficulty Levels

    I want to start taking math one day a week to get the credits done and I'm wondering what the Mathematical ladder is relative to the level of difficulty?
  9. O

    Conservation of mechanical energy (low difficulty)

    Homework Statement There is a rollercoaster. A car starts 35m "high" and descends to the ground. A.) What is the velocity at this point? The car continues an goes 28m above the ground. B.) calculate its velocity at this point. C.) If the car descends another 13m from this point, what is the...
  10. Q

    Difficulty with Sakurai, Ch.1, Problem # 9

    Homework Statement Determine the eigenvector for (S \cdot \hat{n}) |eigenvector> = (\hbar)/2 |eigenvector> where S = (\hbar)/2 \sigma. The sigmas are the Pauli spin matrices and \hat{n} = sin\beta cos\alpha \hat{i} + sin\beta\ sin\alpha \hat{j} + cos\beta \hat{k} You have to solve for the...
  11. C

    How Do Coordinate Frames Influence Equations in Wind Generator Dynamics?

    Homework Statement This is a basic question to a kind of complex problem, any help will be deeply appreciatted. I have all the motion equations for the system described below, but i have a problem with the reference frames... So the problem is as follows: A small wind generator is protected...
  12. D

    Difficulty Making Citations in a Research Paper

    I get the impression that people who review research papers want to see recent papers listed in the bibliography. To me, this implies that I would have to list papers that are not neither the biggest landmarks nor the most relevant. When I do research, it's mostly my own thing. It's...
  13. T

    Difficulty of Theorems: Ranking & Comparing

    How can we rank and compare the difficulty of theorems in different fields?
  14. G

    Difficulty with imagine ( MM experiment)

    HI I have difficulty with imagine why i must see the shift in the interference fringes when we rotate the apparatus 90 degrees ! what exactly happen to make me assuming see this shifting?( in michelson-morley experiment) because when i finish from rotating, the same rays will be...
  15. B

    The level of difficulty of complex variables vs. Real analysis

    Which course is more difficulty in terms of which subject contains more rigorous proofs, Complex variables or Real analysis. I don't know whether I should dropped Complex variables, but the only reason I am taken it is because of the useful physics applications found in this course. I my...
  16. Topher925

    Difficulty leaving my current position, need advice.

    Well, I plan on leaving my current job as an electromechanical engineer on a venture capital project and starting grad school this fall to eventually get my PhD. However, I'm having a lot of trouble leaving on good terms. I'm giving them written notice in person with my last date of employment...
  17. T

    Programs Math for Engineering Minors: Diff. Eq. + Difficulty?

    I am currently an electrical engineering major at Fenn College of Engineering. I passes calculus 1 with b and calculus 2 with b and calculus 3 with a and linear algebra with A. Also took pre calculus if that counts. How much more math I need for minor besides differential equations? Also is...
  18. B

    Having difficulty with an Ax=b problem and understanding it

    I'm having trouble with Ax=b matrices. I get really confused when dealing with matrices that have a different number of rows from columns. An example is this problem: (A is a 3x2 matrix) A = 3 1 4 2 -5 -1...
  19. E

    Courses Electricity & Magnetism course difficulty?

    ive been hearing about this course in the community college i attend and from what I've heard is that this is the hardest lower division physics course that most people take. I am a civil engineering major and the people I've talked to are also engineering majors. any advice for those who have...
  20. K

    How can I calculate the work needed to pull a toboggan up an inclined hill?

    [SOLVED] Work and energy Hello, I've been having difficulty with this question... Homework Statement A 25.6kg child pulls a 4.81kg toboggan up a hill inclined at 25.7° to the horizontal. The vertical height of the hill is 27.3 m. Friction is negligible. Determine how much work the child...
  21. A

    Is Elementary Number Theory More Challenging Than Calculus and Linear Algebra?

    Hello. Can someone shed some light on this: Are the topics Integers, Diophantine Equations, and Congruence supposed to be difficult? How easy are they relative to other topics in first year math curriculum? Like in comparison to topics in Calculus, Linear Algebra, or Physics? Do these...
  22. M

    A minor difficulty in PMF

    I got a minor stuck here... please help me. Ok the stat problem is ... a mail order business has 9 phone lines and x is the number of line in use at a specified time. pmf of X is given: x 1 2 3 4 5 6 7 P(x) .1 .15 .2 .25 .2 .06 .04 Calculate the probability of certain events I...
  23. A

    Difficulty with non-inertial frames

    I seem to be having some trouble processing non-inertial frame homework problems. I hear that sometimes attempting to explain the problem helps with the understanding so here goes. I don't think I have any difficulty visualizing the problems. Creating free body diagrams (FBD) from the...
  24. S

    Calc 2: Is it Really That Much Harder Than Calc 1?

    People seem to think Calc 2 is a very difficult course. Is it that much more difficult than calc 1?
  25. S

    Having difficulty with Ox-Redox

    Hello, Can someone please explain to me something here please? In this oxidation problem Na2Cr2O7 + HNO3 + Na2SO3 yields NaNO3 + Cr(NO3)3 + Na2SO4 + H2O I know S is Oxidized and Cr is Reduced. However, when I look at the solution set, I am get completely confused. They are putting...
  26. M

    Difficulty in understanding a Rocket travelling in space.

    Hi all, I'm afraid this may sound rather trivial but a friend of mine brought up this topic and we're quite confused about it: how does a rocket change its velocity in space? My understanding is that the rocket releases gas, and this gas will cause the rocket to accelerate. If you take...
  27. V

    Simple sound intensity difficulty

    According to the text, at a distance of 50 m from a jet engine, the sound intensity is 10 W/m2. This corresponds to a loudness (or an intensity level) of 130 dB. [You should convince yourself that this is true.] If you find the sound too loud and you want to reduce the intensity by a factor of...
  28. S

    How Does Projectile Angle Affect Range and Distance?

    Homework Statement How far will a stone travel over level ground if it is thrown upward at an angle of 35 degrees with respect to the horizontal and with a speed of 20 m/s? What is the maximum range that can be achieved if a stone is thrown with an initial speed of 24 m/s? The...
  29. B

    Difficulty with washer method when revolving around axis other than y or x axis.

    Homework Statement The region in the second quadrant bounded above by the curve y=-x^3, below by the x-axis, and on the left by the line x=-1, about the line x=-2 Homework Equations It's basically the big radius squared minus the small radius squared, integrated in terms of y, and...
  30. marcus

    Let's try something-let me know if you have difficulty

    Let's try something--let me know if you have difficulty Let's try something. Everybody imagine an expanding three-sphere. When cosmologists give you the balloon analogy, that is what they are trying to illustrate. the balloon is just the 2D analog of the 3-sphere. It is easy to imagine the...
  31. A

    Hi,I have great difficulty understanding some new concepts

    Hi, I have great difficulty understanding some new concepts sometimes. Often I wonder if the door on the days of learning of my brain has been slammed shut. Is it possible that one really can come to understand well, topics which at one time baffle us even in adulthood? I'd like to hear...
  32. W

    Calc II and difficulty of sequences and series

    Ok so I am in Calculus II this summer and its pretty easy so far. However, I have heard the hardest part about Calc II is series and seqence. Why so? And what can I do to make it easier on myself? What was your expierence with sequence and series. Thanks in advance.
  33. B

    How Long Does Light Take to Travel from the Sun to Earth?

    The speed of light is 3.0 x 10 exponent8 m/s. How Many minutes does it take for light to reach the Earth from the sun. Which is 1.5 x 10 exponent11 m away? I know the formula is t=d/v so ?=1.5 x 10 exponent11 m /3.0 x 10 exponent8 m/s The answer is 500s=8.3min...I just don't know how...
  34. E

    Conceptual Difficulty with Stat Mech

    In statistical mechanics, we define \frac{1}{\tau}=\left( \frac{\partial \sigma}{\partial U} \right)_N This formula gives the temperature as a function of the energy of the system and N. So knoweldge of U and N determines the temperature of the system. Conversely, at least when the...
  35. H

    I have difficulty in visualizing the divergence of vector fields.

    Hi all. I have difficulty in visualizing the concept of divergence of a vector field. While I have some clue in undertanding, in fluid mechanics, that the divergence of velocity represent the net flux of a point, but I find no clue why the divergence of an electric field measures the charge...
  36. R

    How Can I Calculate the Downward Force on a Helicopter Using a Column of Air?

    Homework Statement going through my a level text i found a prob i cannot solve Homework Equations 1) a helicopter of total mass 1000kg is able to remain in a stationary position by imparting a uniform downward velocity to a cylinder of air below it of effective diametre 6m. Assuming the...
  37. M

    Can a high-achieving math student solve international Olympiad problems?

    Hi, I am sorry about the length of this but I would appreciate if some you took the time to read and reply. I guess I am posting this because I require a little direction at the moment. I am entering into my last year of a math degree in Australia. I have studied quite a bit of math in my...
  38. K

    QM having difficulty on proofs of operators

    I know this is a simple part of Quantum Mechanics, but I seem to be having trouble with it, I'm not sure if my math is just wrong or if I'm applying it wrong. The questions that I have are: Prove the following for arbitrary operators A,B and C: (hint-no tricks, just write them out in...
  39. R

    Difficulty proving another identity

    could anyone explain (no calculation) how to work the following identity so could get an understanding of it thank you tan(45+A)degrees tan(45-A)degrees=1
  40. R

    What's the Trick to Proving tan3A=3tanA-tan^3 A/ 1-3tan^2 A?

    can anyone help[ me prove the following identity i keep on ending up in a dead end tan3A=3tanA-tan^3 A/ 1-3tan^2 A thank you
  41. quasar987

    Prob - difficulty following exemple

    We perform Bernoulli processes of respective probabilities p and q. What is the probability of getting n consecutive successes before getting m consecutive failures? Sol: We define the following events: E: getting n consecutive successes before getting m consecutive failures. F: The first...
  42. S

    Difficulty solving the following question

    Hi, having difficulty solving the following question.. Any1 can help me and guide me through solving it ?? or is there any good website or reference to recommand ?? Thankz alot..
  43. mbrmbrg

    Colliding particles, level 3 difficulty

    Halliday 7e chapt 4 #16 (with web generated values) In the figure (attatched), particle A moves along the line y = 33 m with a constant velocity of magnitude 3 m/s and parallel to the x axis. At the instant particle A passes the y axis, particle B leaves the origin with zero initial speed...
  44. C

    Relative Difficulty of Math classes

    What is the "organic chemistry" class in math? Is real analysis considered by many to be this type of class? In your opinion, what have been your easiest/most difficult math classes (in ascending order)? Any feedback is appreciated Thanks
  45. DaveC426913

    Music Difficulty of learning musical instruments

    Does anyone know where I might find a rough guide of how difficult it is to learn different musical intruments? I guess I'm specifically interested in the fiddle. I know music theory, I can read music (at least, if given indefinite time) and even mangled a trumpet in high school, but have...
  46. P

    Difficulty with partial fraction decomp.

    I have an equation of the following form: \frac {dz}{z^2 - z} Of course, I factor this into: (z + \sqrt{z})(z - \sqrt{z}) then, \frac{A}{z + \sqrt{z}} + \frac{B}{z - \sqrt{z}} of course cross multiply the denominators to get: A(z - \sqrt{z}) + B(z + \sqrt{z}) = 1 But...
  47. T

    System of equations difficulty

    -44x^2 -2y^2 - 47xy + 45x + 2y + z =0 ; -2x^2 + y^2 + 43 xy + 2x + z =0; x^2 - 44y^2 - 41xy - 2x + 43y + z =-1 _____________________________________ :rolleyes: Can we obtain all REAL solutions of this system without using numerical math tools? I have problems with it and would...
  48. D

    Conservation of Momentum difficulty

    I'm not sure if i did this problem correctly. Could someone check it over. A 730-N man stands in the middle of a frozen pond of a radius of 5.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 1.2...
  49. F

    Difficulty with force problems involving friction

    I finally managed to work through my difficulty with frictionless force problems involving Newton's second law, but now what's throwing me off is how to throw friction into the mix. For this problem, for example: A 68 kg crate is dragged across a floor by pulling on a rope attached to the...
  50. F

    Difficulty with a basic motion problem

    This time I'm having trouble with this problem: If the position of an object is given by x = 2.30t^5, where x is measured in meters and t in seconds, find (a) the average velocity and (b) the average acceleration between t = 1.0 s and t = 2.0 s. Then find (c) the instantaneous velocity v and...
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