Rate Definition and 1000 Threads

Hey guys. I have a very easy math problem which I can't seem to solve. Its been a while since I have had any math. A painting is bought in 1963 for 92,000 pounds, was sold in 2012 10.1 million pounds. Calculate the effective annual return rate and the annual percentage return rate of this...

Homework Statement A resistor with R1 = 25.0Ω is connected to a battery that has negligible internal resistance and electrical energy is dissipated by R1 at a rate of 36.0W. If a second resistor R2 = 15.0Ω is connected in series with R1, what is the total rate at which electrical energy is...

I have tried calculating sampling rates for signals like sinc(200pi t). It was simple and I thought I understood until I cam across signals like sinc(200πt)*sinc2(400πt). I need help with finding sampling rate of these kind of signals and get a clear concept on the topic. Thanks in advance.

Dark Energy is one of the primitive forces of cosmos, existing since early years after Big Bang and its noted that its still is accelerating the rate of expansion of our universe. My question is that what is the source of this mysteries force?People stay that it existed ever in the universe.So...

I am currently working on a circuit design that is featuring both a ADC and DAC. I'll focus my question on the ADC in this thread. I'm trying to figure out what each pin does. Am I correct in assuming that the Vref pin on the an ADC chip is used as the maximum encoded value for a voltage? Say...

Say there is a parcel of air rising and cooling, what is going? Is it that the net kinetic energy (Temperature) of the parcel is distributed over the (new and larger) area/volume? Or Is it that the parcel is undertaking work as it presses outwards and so looses a corresponding amount of kinetic...

In the integration of Force with respect to displacement (W=∫F.dx), is that true if the rate of change of displacement approaches to zero? My teacher said the one which approaches to zero is the rate of change of time. But If I arrange the formula, I will get F=dW/dx then F= lim Δx→0 ΔW/Δx...

Hello, I am working through some reaction engineering problems, and something in particular has caught my attention related more to chemistry I think than reaction engineering. Suppose we have a gas phase reaction ## A + 3B \rightarrow 2C ## If this is an elementary reaction, the rate law is...

Homework Statement A police car is parked 50 feet away from a wall. The police car siren spins at 30 revolutions per minute. What is the velocity the light moves through the wall when the beam forms angles of: a) α= 30°, b) α=60°, and c) α=70°? This is the diagram...

[SIZE=14px][FONT=Lato]So the rate of diffusion is dependent upon the speed of the molecules and the existence of a concentration gradient. What about the concentration of the particles themselves? Diffusion is dependent upon mean free path and concentration is inversely proportional to mean...

Homework Statement For the equation H^2 = \frac{8 \pi G \rho_m}{3} + \frac{H}{r_c} how do I find the value of H for scale factor a \rightarrow \infty , and show that H acts as though dominated by \Lambda (cosmological constant) ? Homework Equations \rho_m \propto \frac{1}{a^3} H > 0...

If I'm losing 30 psi every 20 seconds at a pump, how many gallons am I losing in that time frame? I don't really have a lot of information to go on, which is frustrating. I know the diameter of the pipe is 8" and there's a total length of 500 feet of the pipe. With this info I'm having trouble...

Homework Statement Consider a large plane wall with thickness L whose thermal conductivity varies in a specified temperature range as k(T) = k_{0}(1 + \beta T) where ##k_{0}## and ##\beta## are two specified constants. The wall surface at ##x=0## is maintained at a constant temperature of...

Air pressure decreases at a rate of 2.5 pascals per kilometer in the eastward direction. In addition, the air pressure is increasing at a constant rate with respect to time everywhere. A ship sailing eastward at 10 km/hour past an island takes barometer readings and records a pressure drop of 30...

Hi all, I have a (probably very simple) problem that I need some help with. If I have a body of water in which the temperature of the water, ambient air temperature and mass of the water is known; how do I calculate the rate of heat loss from the water? Using Q=m*cp*(Twater-Tair) I can find out...

The ans is 4. Could someone please help..thanks in advance. :)

I was wondering why when the blood vessels constricted the speed of the blood decreased? I thought that since the flow rate has to be the same, the volume of blood that reaches a smaller area from a bigger area will increase in speed and hence decrease in pressure? Perhaps is this due to the...

Homework Statement mtan for f(x) = 5/√ 3x ... at x=1 Homework Equations msec = y2-y1 / x2-x1 The Attempt at a Solution The two points I got from the equation: (1, 5/√ 3) and (1+h, 5/√ 3+h) msec = f(1+h) - f(1) / h = (5/√ 3+h - 5/√ 3) / h ... multiply top and bottom by denominators (√ 3+h)...

Hi all, I am forced to step outside of my field to investigate a problem that might root in sublimation of solids. I am trying to calculate the mass (after a certain time) of a material that we know is sublimating at , say .000123 g/(cm^2 hr). Is it as simple as multiplying the rate by the...

Hi all, I'm interested in obtaining some measure of contact (or encounter) likelihood between two individuals, each is spatially distributed with some probability density function at time ##t## such that, Space use of individual 1 = ##u(\mathbf{x}, t)## Space use of individual 2 =...

With a given 2kW pump That pumps a liquid with a density of 820kg/m³ from one tank to another that's 30m higher. With a calculated change in pressure to be 241.3kpa. Find the volumetric flow rate. I feel like there are not enough given variables for this problem. What do you think?

Homework Statement The tumbler in an upright clothes dryer rotates at a critical angular velocity so that clothes passing over the top briefly experience weightlessness. If the radius of the drum is 0.30 m, what is this critical rotation rate? (Express your answer in both radians per second...

Homework Statement A 60 kg person is exercising in the gym, doing external work at a rate of 200W. If they have an efficiency of 20%, calculate the rate of temperature increase of their body if none of this heat was able to be transferred to their surrounds. (a) 828 ◦C per hour. (b) 13.8 ◦C...

Hello, I noticed, when deriving rate laws, the assumption is that the reaction is happening in a batch reactor. Does the rate law of a chemical reaction change if put into some type of flow reactor? Thanks

Homework Statement i) At rest a 70 kg person with an area of 1.7 m2 consumes around 14 litres of oxygen per hour. Around 2% of this is provided by diffusion through their skin. Calculate the diffusion rate for oxygen through human skin, in millilitres per second per square metre. ii) What...

I would like to ask for help solving this problem. I've been at this problem for a few hours without making any progress. There is a picture of the problem attached in this thread. So, the question is what is the length of side 'X' used in order to get the shortest possible length for side...

My chemical engineering is a little rusty after 25 years and I could use a little help with this real world problem. This isn't my project but I've been asked to advise. Sorry for the limited information. We have a 30 gallon tank with 75% hydrogen/25% nitrogen mixture at 100 psig. From the...

Homework Statement An unprotected radiation worker walks into a room which she knows is sometimes used to store high activity sources. She is unaware that, on that particular day, it contains an unshielded Co-60 γ source. The source is encapsulated in a material which filters out β...

Hello, In class, my professor said that in a CSTR, the reaction rate is constant throughout a well mixed CSTR. He said in most cases, a PFR will react faster than a CSTR. I can see how the PFR will have a fast reaction rate at the entrance to the tube, and slowest at the exit. However, what...

I want to ask the rate of reaction of organic compound is slower or higher than that of inorganic compound?? I have found an ansswer like that : The organic paricles are molecules. Because of strong covalent bonding within the molecule, organic compounds do not readily react. Reactions...

I know that for a given signal, the sampling frequency Fs must be twice or more than maximum frequency of the signal Fm. It is easy to understand the concept for a 1D signal. But I don't know how to calculate sampling frequency or Nyquist rate for a 2D image. Also what is effect of...

Homework Statement Hi everyone, I am new to calculus. I was recently assigned some homework and am having a difficult time with it. Please help me out. Thank you! A bicyclist is riding on a path modeled by the function f(x) = 0.04(8x - x^2), where x and f(x) are measured in miles. Find the...

I know the universe doesn't expand at a speed but rather a rate over distance but if we take two objects on opposite sides of the observable universe, would they be moving away from each other at a greater rate than light? IE if object A was a star and object B was a planet, would the light...

Hello everyone, I'm new here and new to Matlab. I hope I do place the post in the right place. First of all, thanks for viewing my post. Please bear with my English. I tried my best to explain everything clear. If you have any question about anything I wrote or spot any fault, please tell...

Hello, I am wondering, why is it that ##\frac {d[C]}{dt} \ne k[C]## in general, where ##C## is a chemical species, and the product ##k[C]## is the reaction rate, ##r##. ##r_{c} = k[C]## My thoughts is that because the units aren't necessarily the same, therefore they can't be the same. But I...

Homework Statement Consider: A(aq) + D(l) -> B(aq) + C(aq) Rate Law: k[H+][A] Does the rate increase, decrease, or stay the same, when 500mL of water are added to the solution? Homework Equations The Attempt at a Solution My thought was no. The water doesn't have any effect on the chemical...

I have a sampling process of a very large population in which all items are of type A or type B. I have an analysis of the sampled objects which classifies type A and gives the wrong identification (a false positive) 1 in 1.5 million times. I take a sample of 1 million and find 1 'hit' i.e...

Hi everyone, First post here. Was hoping for some help from a pipeline guru. I am looking into the maximum flow for a pipeline from a reservoir to an outlet about 40m lower. The way I have been looking at it is what is elevation head of the reservoir surface and that is effectively the...

Hi, How to calculate the filling rate of 32mm dia pipe(15m length) arrange vertically from ground to second floor with 0.2bar pressure from main supply? the storage tank capacity is 200gal at the roof of second floor. Tq

Homework Statement The rate of a reaction at 100˚C is four times the rate at 50˚C. What is its activation energy? (A) 1152 kJ. mol-1 (B) 80.1 kJ. mol-1 (C) 54.0 kJ. mol-1 (D) 27.8 kJ. mol-1 Homework Equations k=e-Ea/RT The Attempt at a Solution I plugged in the activation...

I have a molecule with a certain kinetic, vibrational, and rotational energy. It absorbs a photon which excites a vibrational mode. I want to find an equation that describes how the molecules reaction rate with another molecule might change given the added vibrational energy. Is there a name...

Homework Statement For example, let's say we have a container and then we have a hole in the side of the container. Water that is in the container will have a greater flow speed at the hole of the container than let's say at the top of the container, Point A. (point A is subject to...

Hi, I am trying to create an apparatus to measure the thermal conductivity of woody pellet based on peltier effect. the fundamental equation for thermal conductivity is Q"=kA(Δt/Δl), where k is thermal conductivity. A is the area of pellet, Δt is measured by using thermocouple and peltier...

Homework Statement I am trying to calculate the flow rate of the following setup. A bottle with water (density = 1000 kg/m^3) is on a lab stand, and has rubber tubing at the end of the bottle coming down to the benchtop. The top of the water is 17 inches above the benchtop. You insert a...

Dear All, I have an integration probelm and I hope to find a solution for. I assume that an objects moves vertically in the +ive direction of the $y$ axis, from $x=a$, with constant speed $v$. I monitor the rate of change of the angle $\theta\left({t}\right)$. I have derived this rate to be...

I want to pump energy into a chemical species to increase its reaction cross section with another. Typically these species react upon collision when their relative kinetic energy exceeds the activation energy. I want to find a way to increase the reaction rate for interactions at slower...

We know that distant galaxies (which are expanding) are sometimes expanding at rates that do not conform with our known theories and formulas developed by our own observations of gravity. Einstein's theory is of course at the forefront of this conundrum. To explain it some believe that we...

https://www.physicsforums.com/attachments/2883 It was found earlier that $ \frac{dx}{dt}=\frac{\pi}{30} \frac{rad}{sec} $ and $\frac{dy}{dx}=\frac{\pi}{60} \frac{rad}{sec}$ (C) since $s$ and $x$ and are related by the Law of Cosines; What is the rate of change of with respect to time...

Folks, I'm new to this thread. I'm a mechanical engineer, but I haven't done much fluids work since I graduated, 20 years ago. I have a question about calculating gas flow rate, so any help would be greatly appreciated. I have a design that I'm working on that will use a compressed gas...

Hey everyone, sorry I posted this in two different forums. I think this forum was more applicable so I wanted to move it. I have a fluid system of water coming from a pressure source. Then there is a converging nozzle, which I have calculated the resistance coefficient using Crane's Manual...