Volume Definition and 1000 Threads

My understanding is that the amount of heat energy a parabolic reflective surface generates is not the volume of surface area of the mirror, but essentially the volume of surface exposed perpendicular to the suns rays. This effective surface can be also described as the area of shadow that is...

Greetings! I've been brushing up on some thermodynamics recently and came across a perplexing sentence in my notes and text from undergrad. It says that for a combustion reaction, such as the combustion of heptane: C7H16 (l) + 11O2 (g) ---> 7CO2 (g) + 8H2O (l) That this process carried out at...

Homework Statement Water flows over a dam as depicted below. Across section 1 and 2 we have a hydrostatic pressure distribution. Calculate the force on the dam. The Attempt at a Solution My question is regarding control volume. The solution manual has given us this: The two hydrostatic...

Homework Statement If you have a pipe where an incompressible fluid flows. What happens if we get cavitation - can we still say that the volumetric flow rate is "conserved" in the pipe?

Homework Statement A car tyre has initial temperature 23°C and inital pressure 2*105 Pa After heating in the sun, temperature is now 34°C and final pressure is 2.1*105Pa Question asks, Calculate the ratio of new volume to old volume (V1/V2) if the pressure is held constant during the...

Homework Statement Homework EquationsThe Attempt at a Solution Coefficient of volume expansion γ = ∆V/V∆T VT2 = constant Differentiating we get , T2∆V + 2VT∆T = 0 ∆V/V∆T = -2/T So , option 2) looks right . Is that correct ? How do I interpret the answer ? Does that mean the...

Greetings, I have an experiment that pressurizes a small volume at variable rates. 1, 2, and 3 psi/sec. I am trying to think of a way to reproducibly drop the pressure of the container by a known amount while it is being pressurized. Are there valves for this type of experiment? What are...

Homework Statement I have a situation as illustrated by the image above, where the red box illustrates the CV. The pressure on the left side of CV is P1, while the pressure on the right side of CV is P2. Here I´ve directed the pressure forces acting inwards on CV. The problem arises with Fk. I...

Homework Statement Find the volume of the solid between the cone ##z = \sqrt{x^2 + y^2}## and the paraboloid ##z = 12 - x^2 - y^2##. Homework Equations ##x^2 + y^2 = r^2## The Attempt at a Solution I drew a simple diagram to start off with to visualize the solid formed by the intersection of...

Homework Statement Homework EquationsThe Attempt at a Solution I have tried to change mass of oxygen into mol and I got ratio of oxygen and nitrogen. And I don't really know what to do.

$\tiny{t.15.28}$ $\text{Find the volume of the region bounded above by the surface }\\$ $\text{$z=4-y^2$ and below by the rectangle $R: 0 \ge x \ge 1 \quad 0\ge y \ge 2$.}$ $\begin{align*}\displaystyle I&=\iint \limits_{R}4-y^2 \, dA&(1)\\ &=\int_{0}^{2}\int_{0}^{1}4-y^2 \, dxdy...

Assume we have a cylindrical fin which has the effective length of L and its efficiency is given by the equation: $$η=exp(-0.32mL)$$ where $$m=\sqrt{\frac{hP}{kA}}$$ where P is perimeter and A is the cross sectional area of the fin. If the volume of the fin remains constant, which of the...

I have recently read that physicists are exploring the possibility that the universe is a 3-torus. I have been trying to find the formula for the volume of a three-torus online but cannot find it. Can anyone tell me the formula?

Homework Statement A radio speaker produces sound when a membrane called a diaphragm vibrates, as shown above. A person turns up the volume on the radio. Which of the following aspects of the motion of a point on the diaphragm must increase? a) the max. displacement only b) the average...

''1 volume of hydrogen + 1 volume of hydrogen + 1 volume of oxygen = 2 volumes of water vapor'' Now my questions are as follows: 1. How many hydrogen molecules in 1 volume of hydrogen? 2. How many oxygen molecules in 1 volume of oxygen? 3. how many water vapor molecules in 2 volumes of water...

Long time no see, PhysicsForums. Nevertheless, I have gotten myself into a statistical mechanics class where the prof is pretty brutal and while I can usually manage, this problem finally has me stumped. I'd like to be nudged in the right direction, not outright given the answer if possible. I...

Homework Statement Calculate the volume of a sphere of radius ##r## in the Schwarzschild metric. Homework Equations I know that \begin{align} dV&=\sqrt{g_\text{11}g_\text{22}g_\text{33}}dx^1dx^2dx^3 \nonumber \\ &= \sqrt{(1-r_s/r)^{-1}(r^2)(r^2\sin^2\theta)} \nonumber \end{align} in the...

Hello everyone ! I try to find the expression of the time derivative of the entropy for the CMB (photon gas) but I am stuck with the calculations. We are in the matter-domination area and at the present time (Ro=1). No radiation and no vacuum, only the curvature. The different equations are...

Homework Statement A person turns up the volume on a radio. Which aspects of the motion of a point on the diaphragm must increase? a. maximum displacement only b. average speed only c. both maximum displacement and average speed d. neither maximum displacement nor average speed Homework...

Homework Statement Find volume of the solid that lies above the cone Φ = π/3 and below the sphere ρ = 4cosΦ Homework EquationsThe Attempt at a Solution Obviously this is a triple integral. My book tells me that 0 ≤ρ≤ 4cosΦ but this makes no sense to me. From the problem, it lies ABOVE the...

Hello, I would like to know, why is the volume of gas produced during phase change significantly more than the original volume of the liquid being used? Say water changing phase at 1atm.

Homework Statement I am having a problem finding the volume of one compound while having the molarity and volume for another using a balanced equation. This is the problem statement: What volume in mL of ammonium carbonate is needed to react completely with 200.0 mL of 1.500 M silver (I)...

Homework Statement I'm taking an online PChem course where the instructor throws out Z = 3Vr/(3Vr – 1) – 9/(8 VrTr); where Vr is the reduced molar volume. 2. Homework Equations {P + a/Vm^2}{Vm – b} = RT; where Vm is the molar volume Tc = 8a/27Rb ; Vc = 3b ; Pc = a/27b^2 3. The Attempt...

Homework Statement I have two closed bottles one has a smaller volume that the other. (initially atmospheric pressure in both and then closed with a cap) If I heat both bottles up, which one will increase in pressure more the larger bottle or smaller one. Homework Equations PV=nRT ? The...

x = 2y - y2 x = y

I live in a country where people (unfortunately) have a culture of listening music at very high volume in their houses, frequently from their car. However I've been noticing that the sound some of the neighbours sound oscillates from time to time between a high volume and a "low" volume. I've...

Homework Statement A closed container is connected with a tube, water will enter the container via this tube. How would the amount of water in the container affect the pressure in it when water enters the container via the tube? Is this the same as changing the volume of the container (which...

Homework Statement I have an empty cylinder with an external diameter of (23.0 ± 0.5) mm, an internal diameter of (22.5 ± 0.5) mm and a height of (60.0 ± 0.5) mm. I need to calculate its volume with its uncertainty/error. Homework Equations The Attempt at a Solution I do it like this...

Homework Statement Use the shell method to find the volume of the solid generated by revolving the region bounded by the line y = x + 2 and the parabola y=x^2 about the x- axis. Homework Equations - The Attempt at a Solution 1) x = √ (y) 2) x= y -2 V = ∫ (2 π ) ( y ) ( √ (y) - y + 2 ) from 0...

Homework Statement Air with an initial volume of 0.12m³, pressure 1 bar and temperature 18°C is compressed according to the law pV1.3 = c through an 8:1 compression ratio. It is then allowed to expand isothermally back to its initial volume. Determine: i) the pressure and temperature after...

How to find the volume of a block of silver that weighs 107 Newtons

I believe the electric flux within a closed space can be found with the equation phi = Q/ε0. Can this be used for volume and area, or just volume? Also what good does this do. Why would I want to know the electric flux of something?

I'm reading a book on thermal physics and the author says this: "In general, the internal energy will be a function of temperature and volume, so that we can write U =U(T,V) " How do we know this intuitively and how do we know that internal energy is not a function of pressure as well?

i have a problem about find volume of hemisphere I do not know the true extent of radius r (0 to ?) i think... cone ( 0 < r < R cosec(\theta) ) hemisphere (0 < r < R)

Homework Statement I have a function showing the volume of water in a bay at different times in the day, and I want to know what the area under this curve would represent (if it represents anything meaningful). I know how to integrate, so that isn't a problem. Homework Equations I am...

Homework Statement Let E be the ellipsoid x^2 + 2xy +5y^ +4z^2 = 1 Find the Volume of E Homework Equations None, just various integration methods. The Attempt at a Solution I know we're not supposed to say 'I don't know where to start' but with this one I really don't. If the best approach...

Volume of hemi-sphere = ∫ ∫ ∫ r2 sinθ dr dθ dφ i thing (r < r < (r + R)cosθ ) ( 0 < θ < 60 = π/6) and ( 0 < φ < 2π) integral = 2π ∫ ⅓r3 sin θ dθ = 2π ∫ ⅓ [((r+R)cosθ)3 - r3] sin θ dθ i don't know how to find volume of hemi-spere

i don't know to using limit of r ?

Homework Statement a) A mass of 0.12 kg of air has an initial temperature of 500°C and pressure 0.8 MPa. If the air is expanded according to the law pV1.2 = c to a final volume of 90 litres, determine i) its initial volume, ii) its final pressure, iii) its final temperature...

Homework Statement Homework Equations Volume of Sphere = 4/3 pi r^3 d = m/v The Attempt at a Solution my attempt is: r = 2 Vsphere = 32/3 pi cm^3 density of mercury = 13.53 g/ml d*v of sphere = 259.7grams 259.7 grams of sphere * (1/density of mercury) = 259.7g *( 1 ml / 13.53 g) = 19.2 ml...

Hi. If I know the pitch and amplitude of a sound wave, will I be able to calculate its volume. I can understand volume of devices vary betwerb brands and other categories. For the sake of discussion, let's assume volume to be a consistent unit or if db is the right unit, let's take that.

It's been a long time since I've attended school, over 33 years ago. So my question may seem basic to many here. I wish to calculate the partial volume of a cylinder for my excel spreadsheet project. The formula I've found is attached. (unable to type it) But I do not fully understand this...

Hi, I'm doing a pressure test with a liquid medium. I have a fixed volume and I know the pressure drop, and temperature change - how do I calculate volume of liquid lost in a leak?

Homework Statement Here is a pesticide spray vessel, of total volume of 10 litres, containing 8 litres of pesticide. Valve B is closed first,and the space above the air is filled with air at a pressure of 200KPa until the desired pressure is reached, and then valve A is then closed. The...

Positing an empty container, underground, with a static temperature of 50F (both container, earth, and air temperature) and a volume of X... and introducing (and displacing) into this container a parcel of 30F air of volume Y (which is less than the volume of X)... Is there any way to...

Hello I have a question regarding something we wrote in class today. Let ##A## be a bounded subset of ##R^n##, let ##f,g:A\to \mathbb{R}## be integrable functions on A. ##a)## if ## A## has a volume and ##\forall x \in A :m\leq f(x) \leq M## then ##mV(A)\leq \int_{A}f(x)\leq MV(A)## this...

Not sure if I'm posting in the wrong place.

Homework Statement I am working on a problem where I need to determine the time taken for an air heater with an 8kW output to heat a volume of air of 9m^3 by 25C. I am neglecting all losses at the moment. It almost seems too simple in my mind that I'm concerned I'm overlooking...

Hi all, A happy 2018 for all PF members. I have a question. I am trying to understand some basic principle of thermodynamics. My book tells me tge following: "Heating of a gas at a constant pressure uses more heat as when heating the same gas a constant volume" How do i interpret this? I...

Hi .how can i calculate the molar volume and surface tension of nanoparticles ? shoud i have to calculate? or these parameters is available in tables or sth?