I have a few questions about the joule/Newton

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In summary, The concept of a joule measures the amount of energy expended in applying a force of 1 Newton through a distance of 1 meter. This can be seen through examples such as accelerating a 1kg object by 1 meter per second or a 5kg object by 0.2 meters per second. The force and distance remain the same, so the work done is also the same. However, this does not necessarily mean that the objects will have the same kinetic energy as the heavier object will have a lower acceleration rate. Applying a force of 1 Newton through a distance of 1 meter means continuously exerting that force until the object has traveled 1 meter, rather than accelerating the object by a certain amount per
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mpatryluk
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Im not quite sure what it is about this simple concept that i can't get, but I am having a very tough time understanding how the concept of a joule makes sense.

How can it be the energy expended in applying a Newton through a distance of 1 meter?

Isnt a Newton just a measure of force? So it could represent accelerating a 1kg object by 1 metre per second, but couldn't it also represent accelerating a 5kg object by .2 metres per second?
If that's the case, then what does it mean to apply a Newton through a distance of 1 meter? Is that only relevant in cases where the weight is 1kg? Because applying a Newton to a 5kg object over 1m would be a lot more work than that required to do s with a 1kg object
 
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mpatryluk said:
Because applying a Newton to a 5kg object over 1m would be a lot more work than that required to do s with a 1kg object

No it wouldn't. The force is the same, and so is the distance, so work must the same also.

To get a feel for it, think in terms of kinetic energy gained(ΔEk=W).
In the first case, you end up with a heavier object moving slower than the lighter object in the latter case.
The kinetic energy of the 5kg body accelerated by 1 Newton (with 0.2m/s^2 acceleration according to F=ma) over 1m will be the same as the kinetic energy of the 1kg body accelerated by 1N(a=1m/s^) over the same distance.
 
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  • #3
mpatryluk said:
...what does it mean to apply a Newton through a distance of 1 meter?
It literally means you keep pushing with the force 1 N for however long as it takes to travel a meter. It isn't the same as accelerating the object by a certain amount per time over a meter.

Because applying a Newton to a 5kg object over 1m would be a lot more work than that required to do s with a 1kg object
As Bandersnatch shows, applying 1 N to a 5 kg object over 1 m would accelerate it a lot less than 1 N applied to a 1 kg object over the same 1 m.

Imagine expending the same effort throwing a light ball and heavy one. Or imagine taking an engine from a car and putting it in a big truck.
 
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What is a joule?

A joule is a unit of energy or work in the International System of Units (SI). It is defined as the amount of energy required to exert a force of one newton over a distance of one meter.

What is a newton?

A newton is a unit of force in the International System of Units (SI). It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.

How are joules and newtons related?

Joules and newtons are related through the equation W = F * d, where W is work or energy in joules, F is force in newtons, and d is distance in meters. This means that one joule is equal to one newton-meter, or the amount of work done by a force of one newton over a distance of one meter.

Why are joules and newtons important?

Joules and newtons are important in science and engineering because they are fundamental units used to measure energy and force, respectively. They are used in a wide range of applications, from calculating the energy output of a power plant to determining the force needed to lift an object.

How can I convert joules to newtons?

You cannot directly convert joules to newtons because they are measuring different quantities (energy and force). However, you can use the equation W = F * d to convert between the two units, as long as you know the distance over which the force is applied. Alternatively, you can use conversion factors or online calculators specifically designed for converting between joules and newtons.

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