In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, it is often represented as the product of force and displacement. A force is said to do positive work if (when applied) it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.
For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). When the force F is constant and the angle between the force and the displacement s is θ, then the work done is given by:
W
=
F
s
cos
θ
{\displaystyle W=Fs\cos {\theta }}
Work is a scalar quantity, so it has only magnitude and no direction. Work transfers energy from one place to another, or one form to another. The SI unit of work is the joule (J), the same unit as for energy.
I am post-processing a simulation.
A spherical is meshed by many little triangles. A time-dependent pressure (p=10*t) is equally applied to the inner surface of a spherical in the normal direction all the time. After t1=0.1s, the spherical is broken, and each little triangle is disconnected...
I'm wondering what's the difference between work done on quasi-static and non quasi-static expansion.
In a quasi-static process, the gas inside the system must do a work to "extend".
However, in a non quasi-static process, where the gas inside the system doesn't move fast enough to "push" the...
Hi all,
I just read this article about how electrical transformers work and have some questions.
https://www.dfliq.net/blog/the-basics-of-electrical-transformers/#:~:text=The%20three%20important%20components%20of,magnetic%20flux%20is%20initially%20produced.
i). What exactly is magnetic...
Suppose I'm considering a system of N particles that are constrained in their possible motions and so there are less that 3N generalized coordinates. Suppose now I perform a virtual displacement on one particle, which due to some constraints might force some other particles to more virtually...
In its path to the exit it is, disassociated, and still trapped in this enclosure with only a path forward. So now it is in two forms of gas, so the pressure of the expansion in the enclosed enclosure and now traveling at high speed towards the exit, and most likely ionized. It is then subjected...
In this 2D figure below, I can place:
a motor at O
a motor at J
gravity on each link
I can use Hamilton's principle, modified to the principle of virtual work and I can compute the motion of the linkage system.
I do not have to account for these force FOUR forces (in this planar problem)...
Hi, everyone! There are a lot of work energy conservation laws and I get confused which one of them summarizes all of them. Which one I should keep with me and rest should be easy to derive on spot ?
1. ##\Delta E_{mec}=0##
2. ##\Delta E_{mec}=W_{ext}##
3.##\Delta E_{mec} + \Delta...
Hi guys, I'm about to start my degree in a few months and I know what field I want to major in but I don't know what track I should take. In the future I want to work with rockets and spacecraft engines, I want to help develop the new generation. Correct me if I'm wrong but it's called a...
This brief worked example from a textbook section on the method of images is confusing me.
Specifically I am confused about the vector α in the integral on the last line.
When α (or θ) is an angle, I've only ever seen the vector quantity α (or θ) as a polar vector in the plane. But here...
I did a prac where we tried to calculate the rydberg constant for hydrogen. We had a hydrogen lamp and we used a spectrometer that was hooked up to a photomultiplier tube to detect the wavelengths of light corresponding to the balmer series. In one section I need to write up a brief summary of...
Ubuntu 22.04.1 has been released recently, and the Software Centre shows that my system is ready to upgrade. I want to upgrade, but I am a bit afraid because there is no option to rollback the upgrade. I have a number of applications that are essential and I need them to work properly:
MATLAB...
Hello !
I've got a problem understanding what are Lumens and how do I look at lux as well.
For example here :
It makes 800 Lumens in 1 m^2. Does it mean that in every direction in 1m^2 there are 800 Lumens ?
Or when I have a light bult with 800 lumens :
Those 800 Lumens in light bult...
I recall that there was an argument from Born expansion showing that exchange of odd spin between equal sign charges generates a repulsive potential, and if the charges are different or the spin is even the potential is attractive.
I wonder, how does it work for non abelian gauge theory...
just hypothetical question,
First off I am not very knowledgeable in pumps. Let's say you have a pump to pump fluid, i don't think the type matters, self priming as I understand it creates a vacuum with the air in the system to pull the fluid towards the gear pumps.
I'm wondering what happens...
I already know the solution to this, all you do is set the height of the top of the trampoline to 0 and solve for initial velocity so the equation for the conservation of energy $$mgh_0 + \frac{1}{2}mv_0^2 + \frac{1}{2}kx_0^2 = mgh_1 + \frac{1}{2}mv_1^2 + \frac{1}{2}kx_1^2$$ becomes...
Hello
The formula Mgh is commonly accepted as the work done by raising a mass by a distance h, where M is defined as the mass of the object raised.
However, is this really the mass, or the weight, simply obtained by weighing the object? If it's the weight, then doesn't the equation...
I tried using the 109 J to convert to seconds but that didn't work. I also looked through the energy equations but nothing worked. I am not sure how to find time.
Hello physics researchers, teachers and enthusiasts.
I notice one little thing is confusing me in the derivation of Bernoulli's equation in the article, they write:$$dW = dK + dU$$where dW is the work done to the fluid, dK is the change in kinetic energy of the fluid, and dU is the change in...
Hi! So, I've actually already solved this problem.. for the most part.
I have split up the work into two sections, floor 0 to 10, and floor 10 to 15.
From floor 0 to 10, I did
## F_{elevator} = w_{pass.} + w_{elev.} ##
## F = (70)(20 (num. of pass.))(9.8) + (800)(9.8) ##
## F_{elev.} = 21560N...
Hi. I'm a high school student interested in applied math, including but not limited to climate modelling, auto differentiation, and simulations. It'd be really nice if I could get some experience in those fields in a structured learning environment, like an internship, with mentors if possible...
A convergent version ( i.e. convergent in the critical strip) of the traditional series for the Riemann Zeta is derived in the video linked at the bottom. It gives the correct numerical values (at least along the critical line, where I tried it out).
But although it works numerically, I'm...
Does Ohm’s Law, V = IR work for light bulbs? It appears not to from my simple experiment below.
In the figure below, I measured the resistance of a lightbulb and found that resistance to be 2.6 ohms.
However, when I connect this lightbulb into the circuit where I measure the voltage across...
I don't understand what I have done wrong in part (c) I have the initial velocity for the second part of the motion and have the final velocity zero and then the net work done is W_mg + W_Fs and the actual answer for x is 2.37m
Could I get some help/tips please, thanks in advance.
Here is my...
I'm very skeptical of supplements and other products that supposedly boost testosterone and brain health. They are always on TV, and I wonder if they are just snake oil OR if there are any ones that actually do benefit the body. My mother takes Magnesium Glycinate every night to keep her...
Hi, I've heard about the EPR paradox as follows: Leave two entangled particles A and B carried by scientists A' and B', with a pair of incompatible properties (eg spin up/down and left/right) in possible Green/Yellow and Blue/Red states. If one measures Yellow state (eg, particle B in spin up...
During a thermodynamic cycle, an ideal thermal machine absorbs heat Q2 > 0 from a hot source and uses it to perform Work W > 0, giving a cold source a heat Q1 < 0 with an efficiency of 20% . How much is the work done as a function of Q1 ?I have 2 question regarding this problem: 1) Why is Q1 the...
This is a thermodynamics question. A gas absorbs 10 000 J of heat , it releases 3000 J and does 2000 J of work. How much has the internal energy varied?
So I did 10 000 - 3000 -2000 = 5000 J so internal energy decreases by 5000 J. But the correct answer is A) it increased by 5000 J . How ?
I'm installing 4 motorized dampers in my basement HVAC, the motor on each unit is 24V drawing 6 watts at 0.25 Amps. I will be powering them from one 24V 40VA transformer. One temperature controller, that uses direct output and has a max output capacity of 10A, will be installed between the power...
Hi there, this question has already been discussed in this forum, however I do not know how to proceed further and if my reasoning is correct.
I start by imagining a downard displacement of the 1kg weight. As a consequence of this, block A moves upward and to the right. Also, block B moves...
I am a mechanical engineer and my experience with electrical systems is almost nil.
The concept of a simple DC motor explained here was quite interesting, especially the need of a commutator part:
And then I checked this DIY simple DC motor here and was confused because there was no...
hi everyone, i need to build a dc motor for my school project. I have used copper wire for the turns (60 turns), wood to build the structure of the armature and commutator. i have used neodymium magnets as my permanent magnets and paper clips as the brushes. I tried using a 9v battery with a...
The equation I know for adiabatic work is W = P1V1((V1/V2)ϒ-1 - 1))/ϒ-1, but this involves ϒ, but I can use ϒ = Cp/Cv = Cv+R/Cv = 1 + Cv/R, does this seem correct? But I still have a P1
a) ##\rho = \frac{I}{c} = \frac{F}{A}## for a perfect absorber
##F = ma## where ##a = \frac{c}{t}##
##\frac{I}{c} = \frac{mc}{tA}##
##I = \frac{I^2 tA}{mc^2} = \frac{P}{A}##
##P = \frac{I^2 tA^2}{mc^2} = \frac{W}{t}##
##W = \frac{I^2 t^2A^2}{mc^2}##
I am unsure what A is. I think it should be...
Hello, I have a little difficulty understanding how sublimation works, from what I have understood so far, the sublimation of ice for example occurs below its triple point (at a certain pressure and temperature but not atmospheric pressure but at a certain partial pressure). Does this mean that...
The heat conduction equation for a semi-infinite slab with a boundary condition of the first kind is as follows:
The problem is delta is a very small number, so the first exponential will tend to infinity. I am programming this in Fortran and it can accommodate values up to magnitude of 310...
Hi guys I am doing a graphic design project and I would need to know how this tests to check if your drink is been spiked works. Whats the chemical that react to the most common drugs used?
thank you so much!
Hi PF!
I'm going through a backtracking tutorial here. That code runs well for me, and is below:
%% LOAD DATA
% Read a table of daily adjusted close prices for 2006 DJIA stocks.
T = readtable('dowPortfolio.xlsx');
% For readability, use only 15 of the 30 DJI component stocks.
assetSymbols =...
I will summarize briefly my reasoning for both letters, since the answer is immediately after that:
A) The work is quasi-static, and the pressure is approximatelly constant and equal to the atmospheric pressure, so the works is $$W = -p\int dV = -p_{0} (V_{0}-V)$$
B) The work is fast, fast...
I'm quite aware that according to Einstein light is a particle and a wave at the same time.
However, I try to imagine how exactly would light expand. A photon must likely have a certain timing for expansion. I mean, after a photon is originated it immedialy multiplies itself into many other...
A recent preprint ( https://arxiv.org/abs/2112.15157 ) seems to imply that the focussing properties of an optical system can depend on the bandwidth of the sensor, and even on that of the associated electronics! It is argued there that if the ‘frame rate’ of the sensor is very high, photons...
Hi,
This post is about a 4-piston, 4 stroke internal combustion engine(ICE).Here is an youtube animation for such an engine.
I actually have 2 questions.
Q1: We have seen in demos and videos that in a 4-piston (ICE) engine, the pistons P1 ,P4 (pair 1) and P2, P3 (pair 2) are in phase when...
It's late/early...I'm procrastinating on a project...
Thought I'd ask a "dumb" question to satisfy my curiosity. I know computers have hardware (physical machine) and software (from the operating system to other programs/apps that can be downloaded onto the hardware to perform certain...
(I do understand there are many ways to formulate the FE method, but I wish to understand this one.)
I understand that Hamilton's Principle is just that: a principle ( a law the recapitulates the equations of motion)
I also understand that the Principle of Virtual Work (PVW) is a reformulation...