Is there proof gravity can not be a energy source?

[spinn_MP]

Again, it is the energy of the ball itself (not of anything else, hand and such) that is considered when pondering about CoE. Undoubtedly, when you're lifting the ball at bring it to height h the ball does have potential energy there (at height h) equal to mgh but it has also a kinetic energy there (at height h) equal to (1/2)mv^2. That is undeniable. The ball itself, not anything else, has under these conditions energy mgh + (1/2)mv^2 the that height h. Now, you hve decided ahead of time that when you lift the ball at height h you'll freeze your hand there (at height h). It is indeed what you are doing but, again, we're interested in what happens with the energy of the ball frozen at that height h. Now, being frozen at height h has no more kinetic energy (1/2)mv^2 simply bevause you (mind you, 'you') have stopped it from moving. Thus, the ball at height h only has energy mgh to recover. The kinetic energy (1/2)mv^2 is lost. It cannot be recovered. CoE is violated.

This is - simply, unbelievable.

Try to get some help, please.

[Omnibus]

Isn't there someone to take care of the spammer @spinn_MP? His impudent disruptions of multiple threads with sheer gibberish should be noticed by someone who can free the forum from nuisance such as @spinner_MP's clutter.

[Omnibus]

The topic is - is there proof gravity can not be a energy source.

That question was already answered. Gravity is not an energy source by definition. Gravity is force. Force is not an energy source.

[fletcher]

Brian33 .. Force = mass x acceleration.

Gravity Force = mass x 'g' ... where 'g' ... = acceleration due to gravity, approx 9.80665 Newton's.

So, gravity is an acceleration, or a field potential, where an object with mass within the field will experience an acceleration, providing it has Potential Energy [Pe = mgh] of Position & is free to displace

.

Once an object is free to move [unrestrained] it loses Pe & gains Kinetic Energy [Ke = 1/2mv^2] - at any height after release the amount of Pe lost [in Joules, which is Newton meters] is exactly the same as the amount of Ke [in Joules] it gained - so a Potential is converted into Kinetic Movement.

Where this becomes relevant to your question is in applying mechanics - Work Done [a physics term] = Force x Distance [displacement] - WD is also measured in Joules [Nm].

This means that Pe; Ke; & Work Done are measured in the same units & are therefore interchangeable [these are Energy equivalents]

In short : ENERGY IS THE CAPACITY FOR WORK !

So, if we know how much Pe a mass has, or how much Ke a mass has, we know how much Capacity for Work it also has [all in Joules].

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So, to summarise, gravity is an acceleration [m/s^2] - but combine that with a mass & we can determine a Force - Force x Displacement = Work Done [Capacity to do Work].

If we do the Work first [i.e. expend energy] & raise a mass in a gravity field to give it Pe of position it can return the same amount of Work back to us, assuming no losses for simplicity.

Does that make gravity Energy ? - No, it is an acceleration that needs a mass to be raised by expending Energy [Input Energy] from something else before it can give back that same Energy [Output Energy].

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So, we need to raise a mass - we fling a ball skywards until it reaches top of climb - we expended a large force for a short period then momentum carries it upward until it can not attain anymore vertical height - take a snap shot there when it is suspended - it has Pe only equal to the Input Energy we gave it to rise to there - it begins to fall & at the moment it reaches the height we began to hoist it from it has the same Ke we gave it to start with, assuming no losses.

That's why gravity is described as a Conservative Force - it can't give back more energy than it received.

[Omnibus]

This has already been explained a numner of times and therefore it need not be repeated over and over again in bulkier and bulkier posts.

One thing, however, shouldn't happen. No further confusion should be instilled in his already confused enough wqy of understanding elementary physics, namely, acceleration should not be equated with gravity. Gravity is not acceleration as any force is not acceleration. If it were acceleration then we will not have the use for the term 'force' or 'gravity' for that matter. And , it is obvious that acceleration is not a substitute for gravity because an apple at rest on a table is acted upon by gravity but it isn't observed to experience acceleration. The most one can say if one wants to mention acceleration and force in the same sentence is to say that when a nody of mass m is moving its acceleration can be expressed as the ratio F/m. That, however, is trivial and one need not dwell into trivialities to overexplain a simple question (with the aim to appear very learned) thus confusing the student.