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Nairaland Forum / Science/Technology / Physicists!!! Help Me To Derive This Equation. (1924 Views)
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Physicists!!! Help Me To Derive This Equation. by Nobody: 11:10pm On May 08, 2015 |
So . . . I'm an amateur inventor . . . and recently I was trying to build something and I just needed this equation to continue. I've been searching for a long time now and I've even asked some people but none seems to know it. I even tried to derive of with newton's laws but to no avail. Here it is. suppose we have a mass M, located at a height H above the earth's surface, what equation can be used to find the power P required to keep it there? Trust me, the above is not as easy as it looks. Please, if you do find it, explain the procedure well abeg. And if there are any constants or values, please indicate. Thanks in advance. |
Re: Physicists!!! Help Me To Derive This Equation. by Besea(f): 11:55pm On May 08, 2015 |
Power = mhg/ t t is time |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 12:59am On May 09, 2015 |
Besea:abeg no. That's not it. The change in height h is zero. If you insert zero into that equation, it destroys everything. Mgh/t is the equation to find the power required to bring the mass to that height. Not keep it there. Hope you grab? |
Re: Physicists!!! Help Me To Derive This Equation. by saintneo(m): 2:46am On May 09, 2015 |
Potential Energy in the object = MgH Kinetic Energy if the object falls = .5Mv2 (v - velocity) v2 = u2 +2gh (h is the height travelled, u = 0) => v2 = 2gh This implies that v changes depending on the height KE = 2M(gh)2 PE = Mg(H-h) Total energy is always constant = KE+PE = 2M(gh)2 + Mg(H-h) = MgH + 2M(gh)2 - Mgh Power = dE/dt ( the only variable in the total energy equation is h) Power = (4Mg2h - Mg)dh/dt This is complicated. The power derived is the power required to push the object of mass M to the height H. This implies that if the object is already on the ground, then h=H and if the object is at height H then h=0 |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 3:45pm On May 09, 2015 |
Am an inventor too, though above amateur,,,,Not quite sure, but let me drop my little contribution mechanical power P,= FV(force *velocity) and V(escape velocity) = root(2gr) r=radius of the earth I.e 6378.137 km P= F * root(2gr).......(escape power I.e power required to escape the earth) since Mgh/t = power to get to the height H power to keep the body at that height = escape power - power to get to that height = MgH/t - F * root(2gr).... .......take this with a pinch of salt/Origin |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 10:47am On May 11, 2015 |
IwillLaff:. . . i'm coming. |
Re: Physicists!!! Help Me To Derive This Equation. by tpiadotcom: 3:33am On Jun 02, 2015 |
Teempakguy: you are trying to hard to sound smart, its not working. why not do some better things with your time instead of being on nairaland 24/7. |
Re: Physicists!!! Help Me To Derive This Equation. by tpiadotcom: 3:34am On Jun 02, 2015 |
btw, no plane crashes plz. if you want to be a terrorist, find the balls to move to whichever country they're currently in. stop being an online wannabee. |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 3:48am On Jun 02, 2015 |
tpiadotcom:You do not know the amount of time I spent trying to derive this equation. The amount of used sheets I threw in the waste bin. The amount of chalk dust I choked on, the amount . . . . of sleepless nights I had trying to figure it out. You . . . review the entire thread and decide that I am a . . . wannabe . . . you think I . . . am trying to sound smart, to whom? Who am I trying to impress? Who are you? My goals are beyond your understanding. I'm not your average person. Just because I uploaded my real picture and not that of a skeleton, does not give you the right to insult me. I am very sure you don't even understand what the question is or you wouldn't have posted the above. Listen, I don't do e-fights anymore so, whenever you see my posts, try not to comment. It's obvious we won't get along much. Thanks. 2 Likes |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 3:51am On Jun 02, 2015 |
tpiadotcom:terrorist? Why would anyone conclude that from this whole thread? |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 11:20am On Jun 03, 2015 |
@op Please Pay no mind to those who are trying to derail your thread With their badbelle. Oboy this your question really tough o Am here to learn from the masters Nice educative thread keep it up |
Re: Physicists!!! Help Me To Derive This Equation. by soldierdollar(m): 7:37am On Jun 04, 2015 |
Since there is no relative motion , it means the object is at rest . Therfore , no work is done ... Mgh or force X distance is zero |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 1:30am On Jun 13, 2015 |
Timflex:thanks man. |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 1:31am On Jun 13, 2015 |
saintneo:I think this requires knowledge of partial differentiation. Am I right? |
Re: Physicists!!! Help Me To Derive This Equation. by saintneo(m): 3:57am On Jun 13, 2015 |
Teempakguy: Just differentiation, there is only one variable involved |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 6:16am On Jun 13, 2015 |
saintneo:mass is also a variable. |
Re: Physicists!!! Help Me To Derive This Equation. by saintneo(m): 7:45am On Jun 13, 2015 |
Teempakguy: In my analysis, I assumed mass to be constant. But if mass is varying, then the equations will definitely change and partial differentiation will be applicable. |
Re: Physicists!!! Help Me To Derive This Equation. by Nobody: 7:58am On Jun 13, 2015 |
saintneo:thanks, I just wanted to clear that up. |
Re: Physicists!!! Help Me To Derive This Equation. by beatsbyj2g(m): 10:44pm On Jun 14, 2015 |
Let's say d object is at a point H above the ground....... Naturally d object if left a lone will fall back to the earth with a force of F=mass*accl due. To gravity So in othe to keep the object floating u will need a resultant force equal to the one above (f=m*g) To find power now Power =force to keep it floating * H /time |
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