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I have a few questions about the joule/newtonby mpatryluk
Tags: joule or newton 
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#1
Jul3114, 09:46 AM

P: 36

Im not quite sure what it is about this simple concept that i cant get, but im 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 couldnt 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 alot more work than that required to do s with a 1kg object 


#2
Jul3114, 10:00 AM

P: 740

To get a feel for it, think in terms of kinetic energy gained(ΔE_{k}=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. 


#3
Jul3114, 10:51 AM

P: 852

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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