Average Definition and 1000 Threads

I just started learning some Stat. Mech by Leonard Susskind's lectures and am in a part briefly overviewing basic probability in general; One of the things brought up was F(i), some quantity associated with the ith state of a system, and the important average of F(i) averaged over the...

Homework Statement . Air, at a flow rate of 30 [N/s], flows through the reducer shown below. In the 300 [mm] diameter section of the pipe the specific weight of the air is 9.8 [N/m3 ]. When flowing through the reducer the pressure and temperature will fall causing the air to expand and...

Homework Statement Letting c(t) =(t2,t,3) for 0<t<1 (Really it's a smaller than or equal to sign) 1. Find the length of the path 2. Find the average y coordinate along the path Homework Equations What we're given in the book: (These equations are not necessarily relevant) (formula 1) l(c)...

Homework Statement Circle all that are correct Homework Equations V(t)=Vocos(wt) The Attempt at a Solution I don't really understand what the question wants when they ask for an average value. Average value of what? And how do you find it. There are a lot of questions with graphs like this...

So I am teaching myself physics in "Physics 1 For Dummies" and I have come across a chapter dealing with deriving equations, this one being the distance through using the average velocity. I have never derived equations before, so be easy on me! So basically it starts off with s=vt (distance...

Person A travels 10.2m/s[forward]. Person B travels 10.4m/s[forward]. Person C travels 3.51m/s[forward]. Find the average velocity for the trio.I added all 3 velocities(just the magnitudes) and divided by 3, but my answer was different from the textbook's. I got 8.0m/s[forward], but the answer...

Homework Statement A person runs 10.0m[E] in 2.0s, then 5.0m[E] in 1.5s, and finally 30.0m[W] in 5.0s. Find the person's average velocity. Homework Equations Vav= total displacement/total time[/B] Total displacement=df=di The Attempt at a Solution [/B] I found the total displacement to be...

Homework Statement The coil in a loudspeaker has an inductance of L = 56uH (or 5.6 x 10^-5 H). To produce a sound frequency of 20 kHz, the current must oscillate between peak values of +2.2 A and -2.2 A in one half of a period. What average back emf is induced in the coil during this variation...

Homework Statement A runner covers one lap of a circular track 40.0 min diameter in 62.6 s . Homework Equations If she covered the first half-lap in 28.7 s , what were her average velocity for that half-lap? The Attempt at a Solution Attempt 1: Initial Distance: 0 m Distance of a half-lap...

Homework Statement See the diagram. Find $$\frac{U_{ef}}{U_{avg}}$$ . Homework Equations [/B] $$ U_{ef}=\frac{U_m}{\sqrt3} , U_{avg} = \frac{U_m}{2} $$ The Attempt at a Solution This one should be easy.I know that official solution probably divided $$\frac{2}{\sqrt3} \approx 1.154$$ (which...

Homework Statement $$R=5 \Omega , C =50 \mu F, L=5 mH$$ are connected in series on voltage source $$u(t)=150 \sin (1000t)+100 \sin(2000t)$$. Find the average power on resistor R. Homework Equations [/B]$$ P=\frac{U^2}{R} $$, $$ U_{ef}= \sqrt{ \frac{1}{T} \int_{0}^{T} u^2(t) dt } $$The...

Hello, I was wondering if someone out there could help me. The question: The speed, v metres per second, of a particle is given as v=8sin2t+3cos2t where t is in seconds. i) Find the total distance traveled in the time interval 0≤t≤1 ii) Find the average speed over this time interval.

How to find the average value of sin2wt? Mod note: Thread locked due to lack of homework template and no effort shown.

Homework Statement what is the meaning of the circled time average there? does it mean ( (ms^-1)(ms^-1) ) /2 ? Homework EquationsThe Attempt at a Solution does it mean ( (ms^-1)(ms^-1) ) /2 ?

Homework Statement A car is moving in a road and its average speed is 40 km/h. Then it moves back in that road by 60 km/h speed. What is the average speed of this car? ( The answer is not 50 km/h ) Homework Equations Average speed= d/tThe Attempt at a Solution I can't solve this. I get 50...

Hello. I've got two questions: 1) In the U.S., what's the average time per week that a graduate student doing a PhD in astronomy work? 2) In the U.S., what's the average time per week that a postdoctoral researcher in astronomy work? Thanks in advance for your answers.

Homework Statement A sprinter runs the curve of this 200 m in 11.61 s. Assume he ran in a lane which makes a semicircle (r = 32.4 m) for the first part of the race. At 3.59 s into the race his speed is 5.9 m/s. At 7.9 s into the race his speed is 8.4 m/s. His speed after the curve was 12.4 m/s...

It seems to me that light travels (in a room) from everywhere, to everywhere else: A complicated, messy, interconnected network of photons of varying wavelengths which somehow avoid ever colliding with each other. This is what allows me to see things, and other people to see other things...

Hello. I read that in astronomy a PhD lasts an average of 6.1 years. But what about postdoctoral research? In astronomy, what is the average duration of doing postdocs before finally getting a real job? (a job as an astronomer; not reconverting to another field to get a job in this other...

Homework Statement Compute the average value of the function: f(x) = δ(x-1)*16x2sin(πx/2)*eiπx/(1+x)(2-x) over the interval x ∈ [0, 8]. Note that δ(x) is the Dirac δ-function, and exp(iπ) = −1. Homework Equations ∫ dx δ(x-y) f(x) = f(y) The Attempt at a Solution Average of f(x) = 1/8 ∫from...

Look at the following derivation: ## p=\frac{im}{\hbar}[H,r] ## if ##H|\psi\rangle=E|\psi\rangle##, then ## \langle \psi|p|\psi \rangle = \frac{im}{\hbar}\langle \psi|Hr-rH|\psi \rangle = \frac{im}{\hbar}\langle \psi|r|\psi \rangle(E-E)=0 ## What's wrong with my derivation or it is true that...

I found two definitions of wigner function on space time. the first uses a Fourier transform of ##\rho (q+ y/2,q-y/2)## the second uses the Weyl transformation and parity operator ## exp (i \pi \theta N)## where N is the occupation number operator. Could you give me a link which shows the...

Homework Statement A 65 kg man jumps at a velocity of 1.8 m/s. The contact time is 0.45 seconds. Find the average force exerted by the man. Homework Equations F=ma+mg The Attempt at a Solution F=65*(1.8/.45)+65*9.81 I'm not sure if the equation has to be divided by the contact time, .45...

Homework Statement At time t = 0, a point starts oscillating on the x - axis according to the law x = a sin(ωt). Find the average velocity vector projection (I assume it means magnitude based on previous questions in the book). Homework Equations The Attempt at a Solution I knew that the...

I saw this answer to the problem: a 0.14kg ball traveling at 50 m/s is stopped by a glove. The glove moves 0.5m. What is the average force exerted by the ball...

Homework Statement A cow runs in a straight line, moving 108 m east in 16.4 seconds. It then turns and runs 93 m north in 7.64 seconds. a) What was the cow's average speed over the whole trip? b) What was the cow's average velocity over the whole trip? Homework Equations average speed =...

Homework Statement A golfer rides in a golf cart at an average speed of 3.1 m/s for 28s. She then gets out of the cart and starts walking at an average speed of 1.3 m/s. For how long must she walk if her average speed for the entire trip, riding and walking, is 1.8 m/s ? Homework Equations...

Homework Statement hey! I saw you've answered this question before... Hi, I would appreciate any help with the following: The coil in a loudspeaker has an inductance of L = 112 microH. To produce a sound of frequency 40kHz, the current must oscillate between peak values of + and - 4.4 A in...

If you're driving in a car and map out all the displacement vectors, you can add the segments to get the total displacement. Correct? Why can't we add the various velocity vectors for the different segments to get the average velocity. ? Could you add up all the velocity vectors and divide by...

Homework Statement A particle having charge 8 nC moves in circular orbit with angular speed of 100 π rad/s. Find the average current produced! a. 0.2 μA b. 0.3 μA c. 0.4 μA d. 0.5 μA e. 0.6 μA Homework Equations Q = I.t The Attempt at a Solution The equation I can think of is Q = I.t. I don't...

I am trying to figure out the flux surface average of a 3D perturbation in a tokamak. For example what is the flux surface average of cos(m*theta+n*phi) at a given flux surface. (Theta and phi being poloidal and toroidal angles respectively?

Assume a very large volume of a gas of a specific molecule. This molecule can absorb a photon and spontaneously quickly re-emit a photon of the same energy before the molecule can physically interact with another molecule. Therefore the energy of these photons never participate in the...

Homework Statement We know: In a measurement of quantum mechanics (basic) the average value is the cosine of the angle between the orthonormal basis of the measurement apparatus and the qubit (vector) entering it. Question: How do we prove this?Homework EquationsThe Attempt at a Solution Can...

I'm not a maths person, so bear with me, but I'm trying to prove that with 3.5kW you could lift the average american male (89kg) to a height (take just as displacement) of 3 storeys (about 9.14 meters) in under 3 seconds. Is somebody able to calculate this for me? Thanks!

Hello, In the Kinetic-Molecular model for gas molecules in a container it is assumed that the square of the x-y-z velocity components is the same, how is it possible that we assume this?

Homework Statement I am in an Intro to EE class and we were given a homework assignment including the following question: Find the average and rms values of the signal: x(t)=3cos(7ωt)+4 I have formulas for average power and rms but they include V & I, however the signal was given as x(t). I...

Homework Statement [/B] A car is stopped at a traffic light. It then travels along a straight road so that its distance from the light is given by x(t)=bt2−ct3, where b = 3.00 m/s2 and c = 0.130 m/s3 . Calculate the average velocity of the car for the time interval t= 0 to t= 10.0 s Homework...

Say you have a gravitational acceleration between a spherical object of mass M and inner radius R and a much smaller spherical object of mass m (essentially point-like) and distance ro away (M >> m) with an acceleration on mass m at any point r given by a = GM/r2 Knowing that the acceleration...

I would just appreciate someone checking this please, I'm not sure of my answer ... Q: Car moves North with constant speed 50 mph for 5 mins. It then turns 45 degree east and continues at 55 mph for 1 min. Find ave. acceleration. For x, y components, Cos45 = Sin45 = 0.7, so for the 2nd part...

Homework Statement Calculate the average potential and kinetic energies for the electron in the ground state of hydrogen. Homework EquationsThe Attempt at a Solution I know that KE = E - <U(r)>. I know that E = (-KZ^2e^2)/(2a0) and I know that U(r) = -KZe^2/r but I can't figure out how to...

Homework Statement Given the following signal, ##v(t)=2\cos (2\pi f_{0}t)+4\cos (4\pi f_{0}t)+6\cos (6\pi f_{0}t)+8\cos (8\pi f_{0}t)## 1. Calculate the signal's average power in the time domain. 2. Calculate the signal's average power in the frequency domain. Homework Equations Didn't make...

Homework Statement Io and Europa are two of Jupiter's moons. Io orbits Jupiter at a distance of 421,000 km in a time of 1.769 days. Europa orbits Jupiter at a distance of 671,000 km in a time of 3.551 days. Compute an average mass for Jupiter. Homework Equations a=v^2/r...

1. Question A 0.145kg baseball moving horizontally at 35.0m/s strikes a bat and is popped straight up to a height of 55.6m before turning around. If the contact time is 0.50ms, calculate the average force on the ball during the contact. Homework Equations p=mv Δp=mΔv=fΔt Ek=0.5mv^2 (?) Ep=mgh...

Homework Statement A system in thermal equilibrium at temperature T consists of a large number of subsystems, each of which can exist only in two states of energy and , where . In the expressions that follow, k is the Boltzmann constant. For a system at temperature T, the average number of...

Homework Statement An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 48 mm and 72 mm. The electric potential of the inner conductor with respect to the outer conductor is -536 V (k = 1/4πε0 = 8.99 × 109 N · m2/C2) The average energy...

Using the Maxwell-Boltzmann equation above, there is an example in my book (Giancoli 4th edition p. 481) where they use this to find the average velocity. I understand that it would just be the sum of all the speeds of the molecules divided by the number of molecules. But then I'm having...

Homework Statement Just before hitting the ground, a partially inflated 0.625kg basketball has a speed of 3.30m/s. Then it loses half of its kinetic energy as it bounces. (A)What is the ball's speed immediately after it bounces?(B) If the ball is in contact with the ground for 9.25ms, what is...

Homework Statement a Write an algorithm to find the median of three distinct integers a,b,c b Describe D, the set of inputs for your algorithm, in light of the discussion in Section 1.4.3 following Example 1.9. This section discusses Average complexity for an algorithm which involves an...

Homework Statement This is not a homework or coursework question for myself. A friend sent it to me and I'm simply looking for assistance in mathematically proving my answer to myself. Here is the question: "A cart rolls across a table two meters in length. Half of the length of the table is...

Homework Statement Homework Equations Pv=nRt The Attempt at a Solution I already calculated V for a single molecule = 3.99x10^-23 m^3 and the cubic root of this volume gives 3.42x10^-8 m. However, I don't understand what I should do next. What does it mean to compare the value I obtained to...