In physics they say ENERGY IS CONSTANT then how will you explain this.................?

Question

wen we lift a body in the air we provide it with Potential Energy n then wen it falls it gets convertated to Kinetic Energy then here we r creating energy n that energy gets destroyed wen it falls thus here we are CREATING ENERGY AND ALSO DESTROYING IT n dat is against da law of energy conservation. So will anyone please explain this. Answer back only if u know da answer i don want CRAP answer. thanking you -ABHINAV

Answer 1

When you lift the body, you convert chemical energy in your muscles into gravitational potential energy of the body. The chemical energy in your muscles came from food you ate, and the energy in the food came from sunlight (directly for plants, indirectly for animal products--somewhere in the food chain an animal ate a plant). The sunlight energy came from nuclear energy released by fusion in the sun's core...basically I can trace this back to the Big Bang. There, we don't know where the energy came from, but all energy originated there.

When the object hits the ground, it and/or the ground deform, even if only a little bit, so energy goes into rearranging the molecules. Sound may be produced, and that will eventually heat the air as the sound dissipates. You may also produce heat at the point of impact. You could even produce a few sparks of light (say by dropping metal onto metal).

The TOTAL energy in the universe is constant, but it moves into and/or out of our "system" by the work done on or by the system. Since we don't want to track chemical energy in muscles or heat energy produced by impact, we say "energy was added to the system by doing work on it when we lift the object" and "energy was lost by the system when it did work to produce heat, sound, deformation, etc on impact."

Answer 2

when we lift an object work is done by our bodies [muscles]. this is done through chemical reactions from our food.

gravitational potential energy = mgh

where m = mass, g = acceleration due to gravity and h = height above the ground.

as the body is lifted, the 'h' increases because the distance between the floor and the object has changed.

it is this change that causes the increase in GPE.

...

it now has a certain amount of energy, due to the increase in h.

when you drop it, gravity causes it to accelerate at 'g' [9.81 m/s^2]. therefore, because it has an acceleration, the velocity is increasing and the height is decreasing.

so:

GPE = mgh = decreasing [due to decreasing h]

kinetic energy [KE] = 1/2 (m)(v^2)

as the v [velocity] is increasing, the KE is increasing accordingly.

NO energy is destroyed or created.

energy has just transformed from POTENTIAL to KINETIC -- there is an equilibrium...

Answer 3

When u drop the body the Potential energy converts into Kinetic energy and when the object becomes stable it turns back into the potential energy..!!! U can't create or Destroy energy...U can juz convert it from one form to another!!

ANother way to explain would be when u drop the body it juz creates the momentum not actual energy, energy is juz being transformed from stored to kinetic!!

Hope it helps!!!

Answer 4

The energy you used to lift the body in the first place is now the Potential Energy and when you release it and it falls the Kinetic energy is the energy being released that you used in the first place to raise the body.

So, indeed the conservation is energy still is in tact in your example.

Answer 5

energy cannot be created neither be destroyed but it can be converted from one form to other see when u lift an object it reaches to its maximum potentail energy when u drop it potential energy gradually begins to drop and kinetic energy is gained and the time will come when both potential energy and kinetic wil be equal and the amount of lost potential energy will be equal to gain in kinetic and when the body struck to earth kinetic wil be converted to sound and heat energy so amount of energy will remain constant

Answer 6

It is hard to talk about energy when R. feynman said that scientist do not really know exactly what Energy is.
We can only experience the out come of energy Interaction in space.
So energy is a phenomena and not a quantity.No physisits has yet proven the contrary.

Answer 7

You pick up a beverage and lift it.
Its center of mass is higher.. it has gained potential energy.
Where did the potential energy come from? Your hand.

You transferred energy to the beverage when you lifted it.

If you could lift it without exerting any force over any distance then you might create energy.. but when you push on it.. force over distance is energy.

And energy is balanced.

Answer 8

1.when we lift something we use energy of our muscles to raise the thing
2.when the thing is above ground the amount of work done in raising the thing is "mgh".
3.so the thing is capable of doing the same work
4.when it is falling under gravity .the potential energy is converted in kinetic energy.but the amount of work done is "mgh"only.
5.when it falls the kinetic energy is converted into "heat","sound"and some is utilized againts friction..

hope it will help

Answer 9

we know that energy may transfer from one to another (as like potential to kinetic) and it is not creating or destroying the energy .
in your case here is going to same thing.

Answer 10

you consume food, food has CHEMICAL ENERGY. u convert a portion of that in to POTENTIAL ENERGY of body then wen it falls it gets convertated to KINETIC ENERGY . when body hit eatrh, it convert it,s energy in to HEAT , and sound (Sound is again potential and kinetic energy of air particales.) heat energy is not lose then. it isspread accross air, and earth. NO energy destruction.