What is Average: Definition and 1000 Discussions

In colloquial language, an average is a single number taken as representative of a non-empty list of numbers. Different concepts of average are used in different contexts. Often "average" refers to the arithmetic mean, the sum of the numbers divided by how many numbers are being averaged. In statistics, mean, median, and mode are all known as measures of central tendency, and in colloquial usage any of these might be called an average value.

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  1. S

    Statistical physics - average length of polymer

    Homework Statement A polymer consits of ##10^{20}## monomers, each 2 nm long. One end of the polymer is hanged at the ceiling on the other end, we have a load of ##4\cdot 10^{-10}g##. Calculate the average potential energy!Homework Equations The Attempt at a Solution Well... I don't know...
  2. C

    Convert between sinusoidal / phasor, find average power, impedance

    Homework Statement http://imageshack.us/a/img834/8450/4y0t.jpg Given V(s)t = 100cos100t volts, find the average power supplied by the source and the current i2t in the network. Homework Equations V = IR V = IZ Z = V/I inductor impedance: ZL = ωLj capacitor impedance: Zc =...
  3. I

    Average energies (thermodynamics)

    http://i.imgur.com/QFRCRZr.jpg (the black numbers are just so i can make references throuhout this thread, they're not part of my notes) (z is the partition function for Boltzmann statistics) so the first four lines is just expanding an expression for the average internal energy of a system...
  4. S

    Thermodynamics - (polymer) caluclate the average potential energy

    Homework Statement A polymer of ##10^{20}## molecules each 2nm long is hanged from the ceiling. The other end of the polymer is attached to a ##m=4\cdot 10^{-10} g## load. Calculate the average potential energy! Temperature is 300 K. Homework Equations ##<E>=<E_p>=\frac{\mathrm{d} (\beta...
  5. R

    MHB Average attendance problem

    Hello all! :D I have a very basic (not basic enough for me apparently) problem. I'm trying to find out on average how many times people have attended an event. There's a total of 12 events. Below is a simplified version of my table with number of events in the first column and number of people...
  6. Labyrinth

    Average of power curve functions

    I have a program that generates a bunch of power curve functions and would like to know what the 'average' function between all of them would be. Here is my data set so far: 4.638013x^0.076682586 4.834884x^0.034875062 4.0432342x^0.13476002 3.8535004x^0.12178477 How do I do this...
  7. M

    Impulse and Average Force. Ball by the Wall.

    Homework Statement A ball of mass m= .25kg is moving with an initial velocity of \vec{v}=(8.0\hat{x}+8.0\hat{y})(m/s). It rebounds from a wall and has a final velocity (after impact) of \vec{v}= (-5.0\hat{x}+6.0\hat{y})(m/s) a.) Determine the impulse exerted on the ball by the wall...
  8. C

    Need advice for an average biology student worried about the future.

    This thread is geared towards biology professionals who have only attained a Bachelors degree in the biology/science related field and who have had a minimum work experience of 5+ years. Long story short, I'm an average sophomore pursing a BS in Biology, age 28 and have already been thinking...
  9. D

    On calculation weighted average of two positive numbers

    Homework Statement Given two positive numbers calculate their weighted average(Note: This is not actually a homework question, but silly me have doubts, so I put it in this category) Homework Equations Two given positive numbers a,b. No separate weights are available to weigh each...
  10. V

    Weighted average question

    Hi guys, I am doing some research into McDonalds and it's international businesses. It's a small study for people who are interested in good company structures. I came across a section in their annual report where they give some weighted average figures but I don't know how they arrived at...
  11. A

    MHB Combination question - Average before same combination repeats

    Hi guys, hoping someone can help me with this. I’ve posted this on a couple other forums and so far I haven't had any kind of solid answer on it! I was always better with words than numbers so I have no idea where to begin with this. So imagine a combination lock with four values in length...
  12. D

    No 2D momentum average for a particle in a box?

    Hello Everyone, Happy Thanksgiving. I have physics issues. I went around the entire boundless universe in the last two days, and found out the Schrodinger forgot to develop the math for the momentum expectation value for a 2-D particle in a box. It's nowhere to be found. I am a chemistry major...
  13. E

    When do we use the average range instead of the average moving range?

    Homework Statement Homework Equations =̿+2̅, =̿−2 =4̅, =3̅ The Attempt at a Solution From what I gather, we can use the sample range, which is the max minus the min, or the average moving range which is the sum of the preceding value minus the current value divided by the...
  14. R

    What Is the Difference Between Average Speed and Velocity in Tyler's Journey?

    Very simple question -- Average speed for a journey Homework Statement Tyler travels a distance (in a straight line) of 18km in 30minutes. iii)Tyler Returns home following the same route in the same amount of time. Write down her average speed and velocity for this journey, explaining why...
  15. W

    Average Grade of Bachelor's Degree in Physics: Seeking Answers

    Hi Physics Forum. I have just finished one of my exams, in my undergraduate physics program. I haven't yet received the result, but my gut feeling tells me that it hasn't gone as usual. This makes me wonder, what the mean grade for the bachelor degree in Physics is (ore what a good average...
  16. S

    What is the average force of gravity between Earth and the moon?

    Show that the average force of gravity between Earth (mass = 6.0 X 10^24kg) and the moon (mass = 7.4X10^22 kg) is 2.1X10^20 N. The average earth-moon distance is 3.8 X 10^8 m
  17. P

    Approximation to an average of integer square roots

    I have stumbled upon an approximation to the average of integer square roots. \sum^{n}_{k=1}{\sqrt{k}/n} \approx \sqrt{median(1,2,...,n)} Sorry I am not very good at LaTeX, but I hope this comes across okay. Could anyone explain why this might be happening? In fact, I just discovered that...
  18. V

    Average induced EMF and average induced current of a flipped loop?

    Homework Statement A wire loop of resistance R and area A has its normal along the direction of a uniform magnetic field, B. The loop is then flipped over in a time Δt so that its normal is opposite to the field. a) Calculate the average induced EMF. b) Find the average induced current. c) If...
  19. U

    What are the average and transition energies for a muonic hydrogen atom?

    Average Separation of Muon and Proton Homework Statement A muon is a particle with a mass of 206.7 me where me is the electron mass, and with the same charge as an electron. It can be captured in "orbit" by a proton to form a muonic hydrogen atom. a. Find the average separation <r> of...
  20. P

    Force to average acceleration

    I know that there is an equation for an accelerating object that is already a notable fraction of the speed of light (force = gamma^3 * mass * acceleration), but gamma is changing while the object accelerates so what i want to know is how to calculate the average acceleration of an object when...
  21. C

    Potential at center of polyhedron = average of potential on surface

    Homework Statement A closed volume is bounded by conducting surfaces that are the n sides of a regular polyhedron (n = 4,6,8,...). The n surfaces are at different potentials Vi, i = 1,2,3,...,n. Prove that the potential at the center of the polyhedron is the average of the potential on the n...
  22. T

    Solving a Car Coasting Downhill Problem: Average Retarding Force

    A 1200 kg car start from rest and coast down a uniform grade, at the bottom of which ti has a speed of 20 m/s. If the car has traveled 800 m along the grade and has descended 35 m, what is the average retarding force(friction) encountered by the car? How would I solve this problem? I know Fx =...
  23. W

    How Is Average Force Calculated in a Football Collision?

    Homework Statement A football player whose mass is 85 kg throws a football with a mass of 0.8 kg against a post. The football hits the post traveling horizontally with a speed of 25 m/s, and then it bounces back with about the same speed. The football is in contact with the post for 0.05 s...
  24. B

    Can an average student succeed in Research/Academia?

    I want to become a researcher in physics (or some other scientific field) but unfortunately my undergraduate grades in physics have so far not been too spectacular i.e. a low 2:1 in the UK. When looking at career profiles of various people in research areas I have considered, everyone seems to...
  25. T

    Comparing Average Translational Kinetic Energy and Internal Energy of GD and GM

    Homework Statement Two closed containers A and B contain equal number of moles of ideal gases GD (diatomic)and GM (Monoatomic) ,respectively. Q .1 a) If the temperature of gases are same,which of them has more average translational kinetic energy ? b) Which of them has more...
  26. E

    Average acceleration given three velocity vectors?

    Can someone explain this? http://puu.sh/4LNE6.png What is the relevance of t1 < t2 < t3
  27. Ascendant78

    Schools Difference between top colleges and the average college?

    I'm a physics major in my second year of undergrad. I am taking physics 1 and am also trying to study the MIT opencourseware for physics 1 in conjunction with my course. I have to say, the MIT course seems FAR more comprehensive and requires a lot more study time to get it all down. Maybe it...
  28. A

    Calculating Average Force for a Baseball Batting Exercise

    Physics average force need help! Homework Statement A coach is hitting pop flies to the outfielders. If the baseball (mass = 145 g) stays in contact with the bat for 0.09 s and leaves the bat with a speed of 84 m/s, what is the average force acting on the ball? Homework Equations...
  29. S

    Average Power Output for 260000 kg Jet at 9200m Altitude

    Homework Statement 620 seconds after starting its take-off, a 260000 kg jet reaches its cruising altitude of 9200 meters and flies with a speed of 235 m/s. Neglecting friction, what has been the average power output of the engines? Homework Equations ΔKE = Work Power = Work/time...
  30. C

    Average force during a collision

    This isn't actually a homework problem, I'm just wondering what I'm doing wrong: Homework Statement Say we've got a stationary brick wall, and a blob of jello with mass m is launched at the wall with speed v. The blob has length d along the direction of motion. The blob splatters...
  31. A

    Wave Pulse - Finding Average Transverse Acceleration of Segment

    Homework Statement A traveling wave pulse is shown in figure 1 below, traveling at v=6 m/s across a string. In figure 2, a short segment of the string is shown zoomed in. The angle of this string goes from θ1 = 17o to zero within a small horizontal distance Δx = 3 mm. Homework...
  32. A

    Physics linear momentum/ average force

    Homework Statement A very hard rubber ball (m = 0.2 kg) is falling vertically at 3 m/s just before it bounces on the floor. The ball rebounds back at essentially the same speed. If the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball...
  33. S

    Calculating Average Velocity from Acceleration?

    Homework Statement This is a real world application I'm attempting to solve, but I'm unsure how to get started. I have three contiguous segments of equal length and I know the average velocity for the first two segments. Assuming constant (but unknown) acceleration, how can I calculate the...
  34. L

    Michelson interferometer average power derivation

    Homework Statement Using the trig product identity, cosαcosβ=\frac{1}{2}[cos(α+β)+cos(α-β)], show that the time-average power at the detector can be written as Pavg = 1+cos(δ) That = is supposed to be a proportional symbol. Homework Equations Other than the ones given in the problem...
  35. C

    MHB Find the average speed of the ball

    the height in ft of a baseball, t seconds after being thrown straight upward, is given by h(t)=36t - 16t^2 1) find the average speed of the ball for a) 0≤ t ≤1 b) .5≤ t ≤ 1 c) .9 ≤ t ≤1 the answer to a) is 20 ft/sec, which is what you get if you plug 1 into the equation. the answer to b)...
  36. J

    Average value for integrals

    Homework Statement I have a question can the average value for an integral be negative. I don't see why not just checking. You know this evalutation f_ave = (1/b-a) ∫ f(x) dx Homework Equations thx The Attempt at a Solution
  37. E

    What is the magnitude of the average force required to stop a

    Homework Statement What is the magnitude of the average force required to stop an 1500kg car in 8.0s if the car is traveling at 75km/h ? Homework Equations The Attempt at a Solution
  38. MarkFL

    MHB Jaden Harris' Velocity Ques. at Yahoo Answers

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  39. P

    Average Energy and the Equipartition Theorem

    The Equipartition Theorem states that each quadratic degree of freedom contributes 1/2 kT of energy. This can be derived for the translational degrees by integrating the average kinetic energy multiplied by the Maxwell velocity distribution: \int_{-\infty }^{\infty } \frac{m v^2}{2}...
  40. D

    Distance Traveled & Average Speed

    Homework Statement A driver maintains a steady speed of 30.0 m/s for 55 min and then slows to 10 m/s for the next 5 mins. Determine the the total distance traveled and the average speed for the trip. Homework Equations a = v−v0/t The Attempt at a Solution a = 30 - 10 / 60...
  41. S

    Chemistry Average distance between gas molecules

    Homework Statement Show how you would find the average distance between gas molecules at a specific volume, pressure and temp? Given; Pressure=P (torr) Temp=T (Kelvin) n=number of mol N=number of molecules Volume=V (cm)^3 Homework Equations pv=nRT N=n*(NA)...
  42. W

    How to find the average accleration on a velocity time graph

    My physics problem ask me to find the average acceleration on a velocity time graph. On the graph, velocity is at -6 constantly from 0 - 5 s. I know that an question to use would be average accerlation = delta v/ delta t The problem is I did that and I still got it incorrect on...
  43. D

    Find average and rms values of the waveform

    Homework Statement The problem is located here http://www.chegg.com/homework-help/determine-average-rms-value-waveform-depicted-fig-1136-chapter-11-problem-26e-solution-9780073529578-exc Homework Equations Rms=sqrt(1/T∫ from 0 to T of i(t)^2 DT ) Average= couldn't find an equation in...
  44. Y

    Find the average and uncertainty?

    "5 students time a bowling ball traveling from point A to point B. They record the following times": 2.45s 2.49s 2.58s 2.55s 2.51s "7 students measure the length of a car. They record the following lengths": 4.5 m , 4.7 m , 4.4 m , 4.6 m , 4.8 m , 4.5 m , 4.6 m Homework Equations...
  45. L

    Calculating Average of COS2X over a Sphere

    hi, how can I calculate average of cos2x ? I want to take average over a sphere I tried to do like this: <cos2X>= 1/2π ∫cos2xdx and I get 1/2 but in my books, wrote that average of cos2x , taken over a sphere, is 1/3
  46. C

    95% Confidence of weighted average

    Hi all, It's been a while since I have asked a question here, but statistics has never been my forte. I have the feeling that although I know the definitions I do not completely grasp the concept of confidence intervals. Unfortunately I do need to come up with something sensible here. The...
  47. caffeinemachine

    MHB Sum of squares of average change is less than

    Hello MHB, I have no good ideas on how to go about solving the following: Let $f:[a,b]\to\mathbb R$ and $g:[a,b]\to\mathbb R$ be real values functions both of which are differentiable in $(a,b)$. Show that there is an $x\in(a,b)$ such that...
  48. J

    Understanding the Definition of Average Power in Sinusoidal Functions

    I am slightly confused by the definition of average power if the power function $p(t)$ is sinusoidal. Why is it that only one period is considered? I mean I know that it simplifies calculations but if we assume that the period of $p(t)$ is $T$ and I compute the average power over...
  49. P

    Admissions Ph.D. admission in Europe with average grades, no recommendations

    I am a second year M.Sc. Physics student in an Indian university, I am highly motivated to pursue a carrier in theoretical high energy physics. I am willing to get a Ph.D. from a European university(as they have 3 year Ph.D. programs, unlike a 5 year program here in India and US). But the...
  50. M

    Average size of connected components in grid

    Start with an infinite 2d grid of cells, with each cell randomly colored black or white (50% chance). Now take the graph G whose nodes are the cells, and with an edge (A, B) if A and B are adjacent in the grid, and the same color. What is the average size of a connected component of G? Is it...
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