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I need help understanding how Joules and Newtons relate to one another.

They don't. Newtons express force, similar to voltage and Joules express energy as in ergs and watt-seconds.

 

.........................And a Joule It is equal to the energy transferred (or work done) to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. Where does the time componet go to? I know the difference between Joules and Watts but not how to reconsle Joules and Newtons. ................

You stated the relationship between Joules and Newtons in the first sentence above so you've already reconciled the two.
There is no time component to Joules and Newtons.
A Watt is a Joule per second, so Watts do have a time component.

 

I get that, but 1 newton is the energy it takes to accelerate one kg 1 meter each second, per second...so if I have a 1kg ball and I roll it hard enough to make it move one meter in a second, thats one newton. However if I take a square of the same weight, and push it WAY harder and move it 1 meter in a second, did I only produce one newton of energy? I know I used more energy than that due to friction, Also I know that if I instead lift it into the air but extend my arm, due to force multiplied by distance I will have to generate more force to lift it. Can anyone help me with this?

Then, you have the fact that its per second per second, which means in one moment its moving 1m/s the next second 2m/s and so on, why doesnt this appear in joules? And how to you expand on this equation? If there was no time componet, why does it say per second per second, isnt the force defined by how fast youre making the object move? However if you have a ball on an ice rink of 1kg you can make it move much more rapidly on ice than on crushed gravel, make it travel faster per unit of time, I need help understanding how you can have a unit of time within newtons and that doesnt translate to joules. I feel like im confusing myself when I read the definitions of joules and watts

 

Well seeing as everyones still here there is one thing I want to clarify as I´m about to start chapter 3 in the DC Electronics Textbook. The difference between Joules and Watts is merely a time constraint yes? If this is so, I need help understanding how Joules and Newtons relate to one another. Being that One Newton of force is the force required to accelerate an object with a mass of 1 kilogram 1 meter per second per second. And a Joule It is equal to the energy transferred (or work done) to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. Where does the time componet go to? I know the difference between Joules and Watts but not how to reconsle Joules and Newtons. Moreover, is there an equation that relates Newtons and Watts? Sorry for all the questions.

You push an object with 1 newton of force over a distance of 1 meter and you have done 1 joule of work on the object. But you could do that work in 1 second or do it in 1 hour - it would be the same amount of work. Power is the rate at which you do work. So (1 Newton* 1 meter)/1 second = 1 Watt. (1 Newton * 1 meter)/ 1 hour = 278 microwatts. In the second case you are only delivering energy at the rate of 278 micrwatts, but you are doing it for a full hour so the total energy delivered is the same as in the first case, i.e. 1 watt over a period of one second. 1 joule of energy in both cases.

 

I get that, but 1 newton is the energy it takes to accelerate one kg 1 meter each second, per second...so if I have a 1kg ball and I roll it hard enough to make it move one meter in a second, thats one newton. However if I take a square of the same weight, and push it WAY harder and move it 1 meter in a second, did I only produce one newton of energy? I know I used more energy than that due to friction, Also I know that if I instead lift it into the air but extend my arm, due to force multiplied by distance I will have to generate more force to lift it. Can anyone help me with this?
................

You are confusing yourself because you are confusing force with energy.
Newton is not energy, it is a force. There is no such thing as a "newton of energy".
If the Newton moves an object then it is converted to energy.
If you accelerate a 1kg object 1 meter per second per second then the average force required is 1 newton.
If friction is involved then you would need more than 1 Newton to accelerate the 1kg, 1 meter per second per second.

If the Newton is applied over 1 meter of distance, that's 1 joule, but that's not the same as accelerating a 1kg object 1 meter per second per second, since the distance required to do that is not necessarily 1 meter.

Incidentally if the you are rolling a 1kg ball, then it will accelerate more slowly since some of the energy is being converted to rotary motion of the mass.

Done't understand your question about the square of the same weight.

 

Rationalizing electrical and hydralic analogy.

Electric:

Separate a positive and a negative charged particle and there will be an E-field between them. E-field is a measure of the force on a unit of charge. In SI units: Newtons of force per Coulomb of charge. The E-field is a vector quantity, i.e. it has a magnitude and direction. How to measure that field? You measure, at the point of interest in the field, the force it exerts on a test particle of unit charge (a Coulomb) and the direction of that force. Which is why E-field is vector with units of N/C.

Volt is not a unit of force. It is a measure of potential energy per unit of charge (Joules/Coulomb), or the amount of energy it takes to move 1C of charge against a 1 N/C E-field. It is a scalar quantity, i.e. it has no direction. This can be understood by remembering that Work (or energy) = force * distance, so for a coulomb of charge in an E-field the change in potential energy of the charge = E-field * distance moved, or in SI units
V = (Newtons/Coulomb)*meters = N*m/C = J/C = Volts.



In the water pipe analogy:

Pressure Gradient (∇P) is in units of Newtons/meters^3; it is analogous to E-field which is in Newtons per unit of charge. These are a vector quantities.

Pressure (P) is a measure of potential energy per unit volume of a fluid (joules/meter^3), or the amount of energy it takes to move 1 cubic meter of fluid against a pressure gradient of 1N/m^3. This is a scalar quantity just like the analogous Volts. Again, Energy = Force * distance, so for a cubic meter of fluid we have P = ∇P * distance, or in SI units (N/m^3)*m = N/m^2 = N*m/m^3 = J/m^3. (in the second term you see the more familiar definition of pressure as force per unit area: a Pascal in SI units).

Summary of the analogy:

E-field (N/C) => Pressure Gradient (N/m^3)
Volts (J/C) => Pressure (J/m^3)

 

Analogy: Think of a highway. 10 lanes (analogous to 10 volts). Imagine a construction zone (restricted lanes - analogous to a resistor). Traffic (analogous to current or electron flow).

You're driving along at highway speed. Traffic slows down because of construction. 2 lanes are blocked, so traffic has to squeeze through the open lanes. Past the construction you're able to go back to highway speeds, but traffic is now lighter because not as many cars are on the highway. They're tied up trying to get through the construction zone. Before the construction zone there were 100 cars per mile on the highway. After the construction zone there are only 80 cars per mile on the highway.

OR if you REALLY want to complicate things: Think of a cheese pizza. It takes so long to cook at a given temperature. Add pepperoni and it will take longer because of the greater mass. But pizza can be dangerous because it causes cholesterol in your blood stream, which can lead to a premature death.

Not doing it for you? OK, put a ping pong ball in a beer glass. Fill the glass to where the top of the ball is even with the top of the glass. Now, drink the beer. Perform the same experiment but use two ping pong balls. It will take you longer to get drunk.

Or just stick to the math and forget pictures.

 

Then, you have the fact that its per second per second, which means in one moment its moving 1m/s the next second 2m/s and so on, why doesnt this appear in joules?

You're talking about acceleration. Gravity is typically expressed in 32 feet per second per second. Horizontal acceleration is likely similar - but I don't know for sure.

 

No there is not. Unless you can think of another process/system that uses perpendicular, invisible, rotating fields.

One half of life is hard work. The other half is hard study.

 

No there is not. Unless you can think of another process/system that uses perpendicular, invisible, rotating fields.

One half of life is hard work. The other half is hard study.

Come on BR; give me a break. I would like to have a rest sometimes.... Too long time working too much...

 

Hello there,

Analogies can be very beneficial but in order to use one you have to know how the system variables relate to each other. If you know that, you have something very valuable.
For example, if you are working in a mechanical system you can use analogies to create a circuit that you can simulate in LT Spice that will emulate that mechanical system. In theory it will behave exactly the same way.

One of the mechanical analogies is called the Force Current analogy. That is of course because force in the mechanical system is analogous to current in the electrical system. Voltage difference is then analogous to velocity difference. This also means that capacitance is analogous to mass, inductance is analogous to inverse spring constant, and of course resistance is analogous to friction damping.
Using a well-formed analogy like this allows us to write exactly the same equations for both systems. For example the spring mass damper system would analogize into an inductor capacitor resistor (LCR) circuit.

Ditto for the fluid system where current is analogous to volumetric flow rate, and voltage difference is analogous to pressure difference. Charge is then analogous to volume.

The water analogy for electricity though isnt made to be taken that far i dont think. It's just supposed to give a rough idea how current flows. We do have the well defined analogy for volumetric flow rate and current, and voltage difference and pressure difference however, so that may help, but i have a feeling that might be a little hard to grasp at first too. So i guess it is better to just think of current as the flow of water, and pressure difference as the voltage difference, and leave it at that. What this tells us is that current flows through an object while voltage appears across an object. Also, that current can be measured at a point but voltage must be measured as being between two points.

The questions will come up, but if you keep asking questions without doing some of the ground work first you'll always be confused about why some things dont seem to work. It is best to start with some simple circuits and go from there, and save some of the questions for later.
For example starting with resistor and voltage source problems can get you pretty far. From there it will be easier to go farther into more complicated circuits with more complicated part types.

So the idea is to start small, hold off on some of the more complex questions, and try to learn the circuit you are studying as best as you can. You can always ask for circuit help right here in this forum.

 

................
One of the mechanical analogies is called the Force Current analogy. That is of course because force in the mechanical system is analogous to current in the electrical system. Voltage difference is then analogous to velocity difference. This also means that capacitance is analogous to mass, inductance is analogous to inverse spring constant, and of course resistance is analogous to friction damping.
.............................

I believe it's inductance that is analogous to mass (simulates inertia) and capacitance is analogous to the spring.

 

I believe it's inductance that is analogous to mass (simulates inertia) and capacitance is analogous to the spring.

There is more than one analogy that can be drawn across energy domains. You are referring to the Impedance Analogy, MrAI is referring to the Admittance Analogy.

 

I think there is a problem using mass as a capacitive electrical element. What is the analogy for a ungrounded capacitor?

 

What is the analogy for a ungrounded capacitor?

A ready set mousetrap?

Edit: if the capacitor is fully charged, of course.

 

A ready set mousetrap?

Edit: if the capacitor is fully charged, of course.

That works for me.
http://ieeecss.org/sites/ieeecss.org/files/documents/IoCT-Part2-14FormulaOne-LR.pdf

http://www.dartmouth.edu/~sullivan/22files/System_analogy_all.pdf

 

I believe it's inductance that is analogous to mass (simulates inertia) and capacitance is analogous to the spring.

To me this (mass-inductor) is the most consistent mechanical analogy and it's in keeping with Maxwell's original 'force is like voltage' energy storage based on displacement (of charge or spring) physics theory.

 

I believe it's inductance that is analogous to mass (simulates inertia) and capacitance is analogous to the spring.

Hello,

As DGElder pointed out, that is a different but also valid analogy often referred to as the Force Voltage analogy.
Current then becomes velocity, and capacitance then becomes compliance, inverse spring constant.
The two main ones are the Force Current analogy and the Force Voltage analogy.

 

I think there is a problem using mass as a capacitive electrical element. What is the analogy for a ungrounded capacitor?

Hello there,

The analogy works two ways:
1. Mechanical to Electrical.
2. Electrical to Mechanical.

I believe what you are referring to is #2 above.

The thing is, these analogies are usually used for #1 above not #2 because electrical networks are simpler than mechanical systems so usually we want to study the mechanical system using an electrical analogy. I am guessing but that is probably why the word "Force" always comes first in the title of the analogy such as "Force Current" and "Force Voltage", because we intend to move from the mechanical system to the electrical system.
There may also be ways around the ungrounded capacitor issue we'd have to look at a simple example as i cant remember how this works offhand. For example, perhaps a capacitor in series with a bottom resistor where there is a constant voltage drop due to a constant current, the mechanical system might be a stationary platform with a sliding platform on top of that with friction damping equivalent to the bottom resistor, and the mass rides on that moving platform with zero friction, and the force is applied to both the mass and the sliding platform. The velocity then becomes the relative velocity between the mass and the sliding platform rather than the usual velocity between the mass and a fixed frictionless platform. The equation will come out the same for both systems.

I happen to like the Force Current analogy because it's used a lot in control theory, but also because i like the idea of having a force that can seemingly come from out of nowhere rather than need a reference ground point. That way we can easily talk about things like F=M*a where we dont need a reference point for that F force and that is the way we often think about force. For example, if we had a truck that weighed 10000 pounds and had zero friction axles and we pushed on it with a force of 0.1 Newton constantly without end, we could eventually reach 1/4 of the speed of light, even with just that small force, and note we did not have to talk about where our feet were located as we were doing the pushing. Of course if we look at the current 'loop' in the electrical network we can only see the one directional equivalent force in the mechanical system, unless we want to consider the feet and road surface and where the wheels touch, etc., which would not be necessary in most cases (ie we slow or speed up the vector rotation of the earth, which is negligible).

BTW, some nice links

 

Hello there,

The analogy works two ways:
1. Mechanical to Electrical.
2. Electrical to Mechanical.

I believe what you are referring to is #2 above.

There's no doubt that Force-Current has more convenience in #1 Mechanical. For electronics the voltage 'across force' and current 'through/rate flow' variables in analogies seem to be more intuitive when you know (or will eventually know) the kinetic energy of the electrical system is not normally in the charge carriers.