Ratios Definition and 224 Threads

In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8∶6, which is equivalent to the ratio 4∶3). Similarly, the ratio of lemons to oranges is 6∶8 (or 3∶4) and the ratio of oranges to the total amount of fruit is 8∶14 (or 4∶7).
The numbers in a ratio may be quantities of any kind, such as counts of people or objects, or such as measurements of lengths, weights, time, etc. In most contexts, both numbers are restricted to be positive.
A ratio may be specified either by giving both constituting numbers, written as "a to b" or "a∶b", or by giving just the value of their quotient a/b. Equal quotients correspond to equal ratios.
Consequently, a ratio may be considered as an ordered pair of numbers, a fraction with the first number in the numerator and the second in the denominator, or as the value denoted by this fraction. Ratios of counts, given by (non-zero) natural numbers, are rational numbers, and may sometimes be natural numbers. When two quantities are measured with the same unit, as is often the case, their ratio is a dimensionless number. A quotient of two quantities that are measured with different units is called a rate.

View More On Wikipedia.org
  1. C

    Estimate top quark branching ratios without calculating

    Homework Statement Hi, I need to get an estimate of the branching ratios of the processes [/B] t ---> b + W ---> b + c anti-s t ---> b + W ---> b + anti-tau nu(tau) without doing the calculations, just a qualitative estimation. I know I have to take into account the way W decays...
  2. E

    Which Gearbox Ratio is Used to Maintain Speed Up an Incline?

    Hi, I don't get the right answer for this question. I don't see where I'm going wrong. I use this equation to get the engine rpm for each gear ratio: engine speed (rpm) = gear ratio X final drive ratio X vehicle speed X 60 / (2*pi*rolling radius) So for first gear I get an engine rpm of...
  3. C

    Checking Diagram for H2, CO, CH4 Reactor Flow Ratios

    I'm about to attempt this question but beforehand I was hoping if someone could just check if my diagram is correct on the basis of the question; A feed stream contains H2, CO and a trace of CH4. Pure CH3OH is produced by means of a reactor (CO + 2H2→CH3OH), separator and recycle with purge to...
  4. J

    Gear Ratios and Constant Power/Torque: find max velocity?

    I'm trying to determine how exactly gear ratio limits velocity. I know that a high torque configuration is generally regarded as low speed, but my calculations do not seem to support that. Basically, I've written a small problem where we have an input gear with constant torque and an output...
  5. A

    Large nuclei to proton ratios reduce repulsion in a nucleus

    Hi, I am new here. I am just reading over my notes for stable and unstable nuclei and I came across this sentence: 'Large nuclei require a higher neutron proton ratio as this adds more nuclear attraction without adding repulsion'. I was wondering why the large ratio would reduce repulsion? Thank...
  6. moriheru

    Proof concerning similar triangles and their ratios

    Homework Statement Prove that similar triangles have equal ratios (ratios of the sides) Homework Equations SSS, AAA, SAS, SSA The Attempt at a Solution I posted a rather messy and incorrect proof and problem statement prior to this and I wish to correct my mistakes now. The ratios of the...
  7. vmr101

    Solve these equations numerically - Stellar Abundance Ratios

    1. Question from a textbook. I have written down the differential equations for part a) and shown part b), but I am unsure of how to tackle part c). 2. This is the Question from the book http://www.m-rossi.com/img/asp3012-1.png Any advice would be grateful. Thank you
  8. Independent

    UK Masters Programs Acceptance Ratios

    Earlier this year I made (under a pseudonym) Freedom of Information requests to a number of British universities, asking for the numbers of applicants and offers for masters programs in physics. Perhaps the data will be of use to future applicants...
  9. K

    Calculating top speed in each gear given the gear ratios and

    Hello, Can you tell me if there is anyway of calculating the top speed in each gear of a vehicle given its horsepower and gear ratios? Since Power = Force*Velocity Velocity = Power/Force Force = Drag Force + Rolling Resistance --> Velocity = Power / (Drag Force + Rolling Resistance) This...
  10. M

    Gear Ratios to Gear Tooth Count

    Hello Ladies and Gents,I am look for some help with designing the gear trains for an orrery (a mechanical model of the solar system) I am planning. I need some advice on how to go about calculating the specification of the gears in the mechanism which I will machine. I will use cycloidal teeth I...
  11. H

    Understanding Bicycle Gear Ratios

    I'm confused as to how gear ratios work in bicycles. I'm given a problem which says that gear ratio = rfront/rear. It then says that the gear ratio changes from 4 to 0.7. Does this mean that the radii of the gears are changing? I'm unfamiliar with gears on a bicycle so I'm not sure if the radius...
  12. S

    Rolling motion mechanics & ideal economical gearbox ratios

    Greetings, mechanical engineers of Physicsforums, I have been struggling with a particular problem calculating an ideal motor RPM for economical highway cruising. The motor I am looking at is the Subaru EE20 Diesel motor. Its torque curve can be found here...
  13. C

    Understanding NPN BJT Transistor: Ic & Ib Ratios

    Hi i have have a small question regrading to a NPN BJT transistor. the DC current gain (beta) is the ratio between Ic/Ib where Ic and Ib are the collector and base currents respectively. Ib is the input current, that's alright , but, i don't get why Ic considered as the output? in NPN BJT...
  14. T

    Comets' High Deuterium-to-Hydrogen Ratios Explained

    Comets have high Deuterium to Hydrogen ratios. They are enriched with extra neutrons. Comets periodically plunge close to the sun. And, the sun generates flares, which generate neutrons. Separately, I wonder if those neutrons come from fusion of solar corona gas, trapped on magnetic field...
  15. Euler2718

    Determining Missing Trigonometric Ratios

    I'm not stuck per say, but I need to know if I have the right idea for solving the rest of these questions. 1. Homework Statement For the following given trigonometric ratio and domain, determine the missing trigonometric ratio. Homework Equations cos\theta = -\frac{1}{2} ...
  16. Mr Davis 97

    Representing ratios with division

    This might seem like a silly question, but why do we use division to compare two quantities, i.e., a ratio? I've always taken for granted that dividing two physical quantities tells how many of one quantity there is for the other quantity, but why exactly does this work? Why don't we define some...
  17. wukunlin

    Optimal Ratios for Beef Marinade: A Beginner's Guide

    Alright, so I bought some diced beef from the supermarket cos they were cheap and decided to just fry them on a non-stick fry pan with only salt and pepper and I didn't like the taste of it at all. Juices flowed all over the place and ended up boiling the meet instead of fry it... bleh. So I...
  18. P

    Astronomy iron ratios in galaxy

    Homework Statement I understand that [Fe/H] ratios can be used to describe metallicity in a galaxy... but I'm having trouble understanding what [element/Fe] ratios should tell you. Anyone have an idea? Homework EquationsThe Attempt at a Solution
  19. J

    Fluids with high expansion ratios that do not leave the liquid state

    Hey guys, I've been doing a lot of research looking for a fluid that has a high expansion ratio that does not leave the liquid state. the idea is that the fluid could either: - using heat will expand and contract using hot and cold cycles - using electricity (not necessarily needing...
  20. M

    What are the driest continents in the world?

    [Driary ratios of continents] Which continent is the driest continent? I think it should be Antartica, but I have found it is Australia. I think so because Antartica is also the largest desert in the World.
  21. C

    Understanding ratios between exponents, me understand.

    1. I need some help understanding ratios between 2 numbers/quantities og exponents: [b]2.Here is the problem, When you take the ratio between 100grams and 1000grams it is 100g/1000g = 0,10 and you can convert this to kilos 0,1kg/1kg = 0,10 and the ratio stays intact, that makes sense. But...
  22. Mr Davis 97

    Division for Ratios: Explaining Value of Fractions

    Why is division used for ratios? For example, if we have 1 dog for every 2 cats, then why can this relation be modeled by the division? Since the ratio can essentially have the value of 1/2 or 2, then what is the significance of these two distinct numbers in relation to the ratio? How does the...
  23. M

    Ratios & Fractions: Understanding the Relationship

    Why can ratios be written as fractions? if there are 5 men in 20 people the ratio of men to total people is 5:20 which is 1:4. But when we write 1/4 it gives 0.25. And 0.25 means the magnitude of each part when 1 is divided into 4 equal parts. So how does ratio and fraction give a...
  24. R

    How to figure out the ratios in which elements combine

    Homework Statement I need to know is how to figure out the ratio's in which the elements in period 2 combine with chlorine and oxygen i.e a method to solve the problem. I 'm currently in 10th grade. Thanks in advance I appreciate the help. Homework Equations None that I know of...
  25. M

    Variations of compression ratios

    Hi,all. What changes the variations of compression rations in diesel and otto cycles which are always used in the engines. Are there any cycles used in automobile engines other than otto, diesel or seillinger?
  26. gfd43tg

    Engineering What are the voltage ratios in an op amp circuit?

    I have to find both of the voltage ratios. This is just ugly algebra. Here is what I came up with, and was wondering if I was correct. Thanks
  27. A

    Vector Ratios: Solving for Unknowns | Homework Help

    Homework Statement question attached Homework Equations The Attempt at a Solution i can't understand III i can't understand what he wants , if he wants the ratio , the ratio between AP and PB was 3/5 which is not the same as OA and OB (λ=3/8)
  28. M

    Why can't we apply trig ratios to any angle of a right triangle?

    Why do trigonometric ratios have to be related to the angle between the base and hypotenuse of a right angle triangle? I am trying to understand why I can't use these ratios to any angle of a right angle triangle. I try to do that in the attached document. It seems to work for all ratios...
  29. A

    FIR Filter and Signal to Noise ratios

    Homework Statement A noisy but slowly-shifting sensor signal is being filtered with a low-pass, finite impulse response filter. What is the mean delay and expected SNR boost (noise standard deviation of output compared to input) for two filter variations: N filter taps uniformly weighted...
  30. D

    Calculating Gear Ratios With Restrictions

    I have three sizes of gears with 14, 34, and 84 teeth respectively. I need an exact 1:60 gear ratio. The problem I am finding is that 14:34 and 34:84 are very close to the same value. 14 and 84 is 1:6, but without a 1:10, that doesn't get me far. The closest I can get is 7:612...
  31. Night-san

    Ideal Gas Law: messing with ratios

    Homework Statement Air is pumped into a bicycle tire. The 43 moles of air initially in the tire have a gauge pressure of 1 atm. How many moles of air must be pumped into the tire in order to raise the gauge pressure to 5 atm? Assume that the volume and temperature of the air inside the tire...
  32. C

    Particle Physics: Partial Decay Widths and Branching Ratios

    Hello there, This isn't specifically homework, it is study. I'm having a difficult time trying to understand how to calculate/estimate partial decay widths, \Gamma[\itex], and Branching Ratios. I haven't found very clear information online so far. Here's just an example below that I'd like...
  33. P

    Exploring the Impact of Increasing Eggs on Apples/Egg Ratios

    If you are given a ratio, say apples to eggs and you were to increase the number of eggs but keep the number of apples the same, would you say that the ratio of apples to eggs is reduced, as when you divided apples by eggs, the number would be smaller if eggs are increased and apples remain...
  34. S

    Engine thermal efficiency and Volume ratios

    The question: A perfect gas undergoes the following cyclic processes: State 1 to 2 cooling at constant pressure. State 2 to 3 heating at constant volume. State 3 to 1 adiabatic expansion. Deduce an expression for the thermal efficiency of the cycle in terms of r the...
  35. S

    Typical energy ratios to get into orbit? (height, friction, velocity)

    I realize the answer depends how where in the atmosphere speed is increased more, and whether a higher orbit or lower orbit is desired, and the shape size and weight of the craft. But I'm just curious about typical ratios. About what fraction of the fuel goes to lifting the weight of the...
  36. Y

    Ratios for 10% Solution: How to Calculate for 4oz/1gal Ratio

    Homework Statement 4 ounces of substance for a 10% solution for 1 gallon of water Homework Equations The Attempt at a Solution 42.68 ounces of substance per gallon? to make a 10% solution in water?
  37. P

    Intuitive thinking about ratios

    I was pondering over this problem about ratios and wondered what does 3/2 (oranges:apples say) actually means. I then understood after giving some thought that you DIVIDE the oranges with the no. of apples so that you get an idea about how many oranges correspond to 1 apple i.e. how much of one...
  38. A

    Logarithmic Ratios: Solving Input/Output & dB to Np

    The current input of a system is 250mA. If the current ratio of the system is 15dB, determine: (i) the current output and (ii) the current ratio expressed in nepers I have the answer to the questions which are (i) 1.406 A (ii) 1.7272 Np I am just struggling with the complexity of the...
  39. S

    High energy electron positron branching ratios.

    Homework Statement Why does the ratio: \frac{σ(e^- + e^+ \rightarrow μ^- + μ^+) }{σ(e^- + e^+ \rightarrow τ^- + τ^+)} tend to unity at high energies and would you expect the same for: \frac{σ(e^- + e^+ \rightarrow μ^- + μ^+) }{σ(e^- + e^+ \rightarrow e^- + e^+)} The attempt at...
  40. paulmdrdo1

    MHB Trigonometric Ratios: Explaining Angle $\theta$

    can you explain to me what my trigonometry book say "the value of each ratio is determined only by the angle $\theta$ and not by the particular point $P(x,y)$ on the terminal side; that is , the value of the ratio is a function of the angle $\theta$." what does "determined only by angle...
  41. K

    Finding Ratios of Velocities After Impulsive Force on Rod of 3 Equal Masses

    Homework Statement Three equal masses are attached to the ends and midpoint of a light uniform rod, which lies on a smooth horizontal plane. One of the end masses is struck by an impulsive force perpendicular to the direction of the rod. Find the ratios of velocities of the three masses...
  42. F

    Dynamics Physics - Acceleration Analysis / Gear Ratios /

    First time posting. Homework Statement Gears A and B, of Masses 4kg and 10kg, respectively, are rotating about their mass centers. The radius of gyration about the axis of rotation is 100mm for A and 300mm for B. A constant couple of C=0.75Nm acts on gear A. Neglecting friction, compute: -...
  43. F

    What Should Be the CT Turns Ratio for a 30MVA Transformer in a Railway Network?

    Hi, A 132kV to 50kV single phase 30MVA transformer supplies an electric railway network. It is to be protected with differential protection using an electronic protection relay that accepts 1A CT inputs. If the CTs are to be continuously rated for a 40MVA load what would be the ideal turns...
  44. N

    Using ratios to obtain the weight of a person at a specific distance

    Homework Statement Assuming the person weighs 980 N on the surface of the Earth, how would you use ratios to obtain the weight of a person at 128 000 km above the surface of the Earth. Homework Equations Fg is proportional to 1/d2 The Attempt at a Solution The answer in the...
  45. Saitama

    Solving the Mystery of Wrench Work Ratios

    Homework Statement (see attachment)Homework Equations The Attempt at a Solution If a force a F acts on the farther end of the wrench, the torque due to it Fl where l is the length of wrench. The work done by this torque for one full turn is Fl*(2##\pi##) For wrench A, l=10 cm, and for wrench B...
  46. H

    Gravitational field strength (ratios)

    Homework Statement A 6.2*10^2-kg satellite above Earth's surface experiences a gravitational field strength of magnitude 4.5-N/kg. Knowing the gravitational field strength at Earth's surface and Earth's radius, how far above Earth's surface is the satellite? (Use ratio and proportion.)...
  47. O

    Finding the ratios of diatomic, monatomic and ionized hydrogen

    Hi, Would a clump of gas in space have some diatomic molecules in it as well? If it does, how do we find the ratio? I know that hydrogen gas at room temperature on Earth is diatomic. So I guess the state of the gas molecules change like this. Diatomic molecules -> Monatomic ground state ->...
  48. O

    Compute Ratio for Luminosity to Mass: Compare to Sun

    Hi hi hi, So guys I'm just having a little trouble with this question.. Compute the ratio between the luminosity from part B to the mass from part A. How does that ratio compare with the Sun's ratio of luminosity to mass? So for part A I got 1Msun and part B I got 1000Lsun So to compute the...
  49. B

    Video help - Fully Expand and Animorphic aspect ratios?

    Video help -- Fully Expand and Animorphic aspect ratios? I converted a lot off my DVDs that are of 1970's TV show Land Of The Lost to avi files so I can watch them on my pc. There is one setting for Aspec Ratio I do not get I know if I pick 16:9 this is for Wide Screen. And I know if I...
  50. K

    D Meson Decay: Neutral D-Meson Branching Ratios

    Hi all, I have a question regarding to the branching ratio of neutral D-meson decay. Give three decays: 1. D --> negative kaon + positive pion 2. D --> positive pion + negative pion 3. D --> positive kaon + negative pion The one with highest branching ratio is 1. due to its non-cross...
Back
Top