Ratio Definition and 1000 Threads

Homework Statement During a tennis volley, a ball that arrives at a player at 40 m/s is struck by the racquet and returned at 40 m/s. The other player, realizing that the ball is out of bounds, catches it in her hand. Assuming the time interval of contact is the same in both cases, compare the...

Hey guys, I'm having difficulty with my university project which is to build an electric bike. My design is to have a friction wheel attached to the shaft of my 800W 2800rpm electric motor which is rated at 2.8Nm. I have two issues with my spreadsheets at the moment. Can someone please help...

http://www.tech.plym.ac.uk/sme/mech226/gearsys/gearaccel.htm Hello, I tried to derive n=N1/N2=omega2/omega1 with using T1=T2 but it is a wrong assumption. I thought they should balance to satisfy Newton's 3rd law, but it is not. Could you explain me why.

In the CODATA table of physical constants, there are very precise numbers given for mass of electron and mass of proton. And an even more precise number for proton electron mass ratio. But when you divide the mass of proton by the mass of electron, you don't get the same number as the proton...

Hi, I am trying to find a NACA-aerofoil for a given wing geometry (AR = 8, Taper: 0.35, Cruise CL = 0.05 at 0.6 degrees angle). Do any of you know if it is possible to find an aerofoil that will give this wing the best L/D-ratio at this cruise AoA (0.6 deg)? I have done some analysis on...

The 7th note has a frequency of L/3 and the 12th has a frequency of L/2. What is the ratio of the two frequencies? I feel like this is really easy but I don't know how to solve this.

What is the heat/cold ratio in thermoelectric modules to generate a specific voltage pls? old Bozo

Homework Statement A small object with mass m, charge q, and initial speedv0 = 5.00×10^3 m/s is projected into a uniform electric field between two parallel metal plates of length 26.0 cm (Figure 1) .The electric field between the plates is directed downward and has magnitude E = 700 N/C ...

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 A particle of mass m and initial velocity v0 collides elastically with a particle of unknown mass M coming from the opposite direction as shown in the left-hand sketch on the next page. After the collision, m has velocity v0/2 at right angles to the incident direction, and M...

Hi all, I'm new to the forum so I hope this is the right place to pose this question. I've managed to find answers to nearly all of the questions I've had regarding certain aspects of physics on the forums, but haven't seen this addressed anywhere. According to Wikipedia (...

Hi, I’m having a problem with a particular case of binomial proportion. I want calculate a confidence Intervals for a binomial proportion for an efficiency. This kind of intervals are usually defined for ratios between integers numbers but in my case I had to subtract from both numerators and...

A common claim that hurricanes and cyclones have geometrical proportions that resemble a logarithmic golden spiral. Knowing that cyclones and hurricanes rotate because of the well-known Coriolis Effect, is it possible that the Golden Ratio is just a natural manifestation of the Coriolis effect?

What's the ratio $\displaystyle \frac{e^{i\sqrt{x}}-1}{e^{i\sqrt{x}}+1}$ equal to? I can't work it out to anything I recognize. :confused: The answer is $\displaystyle i\tan(\frac{1}{2}\sqrt{x})$. I suppose I could work backwards from the answer, but I won't have the answer in the exam.

In the weak field limit, we have dt = (1 + 2\phi)^{-\frac{1}{2}}d\tau where the usual meaning of the symbols applies. This means that in GR dτ < dt analogous to SR. Let suppose we measure the period dtS of a photon emitted at the surface of the Sun as well as the same photon, i.e. same atomic...

1. The problem statement, all variables and given/known dat Show that if you have a signal f and noise σf for a stellar flux measurement, then the uncertainty on the observed magnitude is given by σm = 1.0875 x σf / f Homework Equations (you should use the fact that when ε<<1 then log(1±ε) ≈...

hi i had doubt in hereditary and evolution chapter class 10 CBSE India So now I know that the phenotypic ratio of the pea ( with reference to dwarfness and tallness) is 3 : 1 which can be interpreted as : for every 4 pea plants obtained by a peapod, there are 3 tall plants and 1 dwarf plant...

Dear all, I don't know if this is the correct place for this question, but I did a little search on the forum and I saw that most FFT related questions have been posted here. My question is this: I need to deconvolve two real signals (in my case they are two probability density functions), so I...

Homework Statement Homework Equations KE = 1/2 M V2 P = M V The Attempt at a Solution p = mv pcardinal = .0450vcardinal pbaseball= .144vbaseball 0450vcardinal/144vbaseball Why is this not the correct answer? I know KE are equal so KEcardinal= ½ .0450 v2 KEbaseball= ½ .144 v2 so .0450...

I need some help with something that seems rather simple, but I don't know how to apply the formula. Let's say I have a table and based on the particular material from which it is constructed, it has a strength to weight ratio of 50 kN·m/kg. If I were to place an object on the table that...

Homework Statement [/B] I was wondering if you'd be able to help me with this problem: Given a two-stage launch vehicle with an engine that produces an Isp =400 sec, a payload mass of 10.000 kg, stage 1 structure mass of 10.000 kg, stage 2 structure mass of 10.000 kg, determine the mass ratio...

Homework Statement : A cylinder is elongated by 2% of its original length. If Poisson's ratio of its material is 0.3. Calculate the percentage variation in volume.[/B]Homework Equations V = πr^2l η= 0.3= Δl/l/Δr/r[/B]The Attempt at a Solution I tried using calculus to differentiate V to find...

if : (1)$a,b\in N $, and $a>b$ (2)$a\times b =1364+(a+b)$ (3) eather $a$ or $b$ is a perfect square can you tell which one is a perfect square ? ( $a$ or $b$ ?),and please find $a:b$

Homework Statement See the picture. If at electrical resonance ##U_c=60 V## and ##U_L=40 V##, find the ratio of reactances ##\frac{X_L}{X_c}##.Homework Equations [/B]##Z=\sqrt{R^2+(\omega L - \frac{1}{\omega C})^2}## , ## Y= \sqrt{\frac{1}{R^2} + (\omega C - \frac{1}{\omega L})^2}## , ##\phi =...

Let's assume a universe like ours which after inflation expands decelerated and accelerated thereafter. How will the ratio Hubble length ##1/H## to scalefactor ##a## evolve over time? And how could one calculate the time dependence of this ratio. Any help appreciated.

Hey guys we say that when in periodic table we go from left to right atomic size decreases because of increase in nuclear charge in the same shell but my question is that the electron to proton ratio is 1:1 then how nuclear charge is increased. Some say nuclear charge is concentrated but my...

Homework Statement I have been tasked with designing a feasible experiment to determine the ration between 2 vessels. I think i have a way that works on paper. Homework Equations pV = nRT and the conservation of mass. The Attempt at a Solution 1.Start with 2 vessels of unknown volume x and y...

Homework Statement Potassium 44 (4419K) has a half-life of 20 minutes and decays to form 1420Ca, a stable isotope of calcium. (a) How many atoms would there be in a 10 mg sample of potassium 44? (b) What would be the activity of the same? (c) What would the activity be after one hour? (d) What...

Homework Statement For large intensities, what is the maximum ratio of atoms in N1 compared with N3? I suppose this is just a bit of maths I'm struggling with, seems simple I just can't get it for whatever reason D: Working through previous question, I got to: N3= (Ip/Is) / ((Ip/Is) +1 ) N1...

Hi, I was looking some exercices on internet about the poisson's ratio. I have just one question. How can i calculate the young's modulus and poisson's ratio when i know that a material is purely elastical. I calculate circonferential et longitudinal contraints and i have write the cauchy...

Homework Statement Hi guys (first post here let me know if I can fix anything that I've done wrong), I'm struggling a little with the second part of this question and seem to be going round in circles A column has the dimensions shown in the diagram below. (a) What is the minimum length of...

Homework Statement [/B] Figure 1) Block 1, of mass m1, is connected over an ideal (massless and frictionless) pulley to block 2, of mass m2, as shown. Assume that the blocks accelerate as shown with an acceleration of magnitude a and that the coefficient of kinetic friction between block 2 and...

Suppose a rock sample at the time of its formation 3.6 × 10^9 years ago contained N0[87Rb] rubidium atoms 87 (87Rb), N0[87Sr] strontium atoms 87 (87Sr) and N0[86Sr] strontium atoms 86 (86Sr). From the relative abundance of the three species at the height of the rock formation yielded the...

Hello everyone, i am currently dimensioning a compression system using a vehicle turbocharger and need to find a way to relate the pressure ratio of the compressor and the mass flow rate. (flows trough compressor and turbine are of course separated) For the turbine, one can use Stodola's...

Homework Statement [/B] Find the position vector of point P if P divides AB in the ratio 5:-2 given A (-1,6,4) and B (4,1,-1) The Attempt at a Solution The only trouble I have is to understand the question... Does it mean something like A------------------>B<----------------------P...

I have 3 streams entering my vessel and 2 of the streams are dependent on the 3rd stream's flow rate in a certain ratio. Is there a way to control the flow rate of the 2 dependent streams using the flow rate of the 3rd stream and show it in my P&ID?

1. Homework Statement Calculate the magnitude of the gravitational force between the Earth and a 3.7 kg mass on the surface of the earth. The distance to the center of the Earth from the surface is 6370 km and the mass of the Earth is 5.98·1024. That gave me 36.37 N Calculate the magnitude of...

Homework Statement A crown is made out of silver and gold. Its weight is 58.8 N in air, and 54.8 N when submerged in water. What is the ratio of ##V_{\mathrm{gold}}## to ##V_{\mathrm{silver}}## in the crown? ##\rho_{\mathrm{gold}}=19300\frac{\mathrm{kg}}{\mathrm{m^3}}##...

Homework Statement I need to find the X of two substances using only the data found in lab. Which is: nmixture=1.4156 nbutan-2-one=1.3787 ntoluene=1.4970 For the mixture, I don't know what X (the mole fraction) is. That is what I must find out. Homework Equations nmixture= (Xbutan-2-one...

Object: Black Plastic Lid $C$ = Circumference (cm) $D$ = Diameter (cm) Ratio $= \frac{C}{D}$ Ratio $= \frac{30.75}{9.46} = 3.25$

I was reading this document from CMS: https://cds.cern.ch/record/2002036?ln=en But I have some problems understanding how they calculated the bckg coming from the QCD. My questions come from Sec.6 Background, so you can jump and have a quick glimpse over it (?). They used the tight-to-loose...

$\triangle ABC, \overline{AB}=5,\overline{AC}=6,\overline{BC}=7,$$M$ is the midpoint of $\overline{AC}$ $D$ is one point on $\overline{BC}$,if $\overline{AD}\perp \overline{BM}$, please find the ratio of $\overline{BD}: \overline{CD}$

Homework Statement A ball of mass 65 g is thrown vertically upwards from ground level with a speed of 16 m s–1. Air resistance is negligible. The ball takes time t to reach maximum height. For time t 2 after the ball has been thrown, calculate the ratio of the potential energy of ball to the...

Hi, friends! 1. Homework Statement : I have found an exercise where one should calculate the ratio ##N_{v_{\text{e}}}/N_{v_{\text{rms}}}## between the number of molecules having escape speed ##v_{\text{e}}=\sqrt{(2G M_t)/r}## (where ##M## is the mass of Earth) and those moving at the root mean...

Two identical molecules A and B each of mass M travel with the same velocity towards a vertical wall at an angel 20 degrees with respect to the normal to the wall. A rebounds from the wall with the same speed while B sticks to the wall. Determine the ratio of the implus experience by A to that...

When we change the gears of the bicycle we are riding, we change the the disc we are currently at (which are located at the place where we pedal) to some other disc. This means the radius of the circular disc we were pedaling/rotating changes. So that means if we were rotating the disc with...

Why is the ratio of atmospheric neutrino fluxes expected to be: R= \frac{\nu_\mu + \bar{\nu}_\mu}{\nu_e +\bar{\nu}_e} =2 for no Neutrino Oscillations? An answer that I found gives: \pi \rightarrow \mu \nu_{\mu} \rightarrow e \nu_e \nu_\mu \nu_\mu But I think this is "wrong" in general, because...

I want to mix oil and gas by the tank for my leaf blower. The mix is 40:1 My tank holds 16 oz. The manual says 3.2oz. of oil per 1 gal. of gas. I came up with 2.4 teaspoons of oil to the 16oz. tank. Am I right?. The reason for this question is that I don't use the leaf blower that often and...

I have a 24V, 1500rpm bldc motor.The power output will be around 400W. We are using it to electrically drive a tricycle. How can I calculate the gear ratio to decrease the rpm and increase the torque? The transmission system includes an intermediate shaft with 22 teeth sprocket and 44 teeth...

Homework Statement I have a set of data that I need to use to calculate the stator to winding turns ratio. A hint was given: "The rotor current measured is the rotor winding current. However, the rotor current we use for our calculations is the current referred to the stator side of the...