How to derive x(t) equation from energy

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The discussion focuses on deriving the equation x(t) from energy principles, specifically using the integral involving potential energy V(x) and total energy E. The initial approach using E - 0.5mv^2 led to complications, as it resulted in an unhelpful denominator. A key realization was that substituting initial conditions with v0 and x0, while setting t0 to zero, clarified the integration process. Ultimately, the correct formulation allowed for the derivation of the desired equation x = x0 + v0t + at^2/2. The thread highlights the importance of correctly applying initial conditions in energy equations for successful integration.
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1. Using V(x)= -max, in the following equation:
\int_{x_0}^x \frac{dx}{\pm \sqrt{{\frac{2}{m}\{E-V\left( x\right)\}}}}<br /> \ = t - t0

to get:
x = x0 + v0 + at2/2

E is total energy and V(x) is potential energy. I have tried hard integrating it in various ways but do not seem to get the required result.
I would really appreciate in help or tips in this regard.When I use E - 0.5mv^2= V(x), the denominator becomes v and really does not help at all. If I do not do that, and use V(x) = -max that does not help either. I do not seem to be reaching the required equation in any way.
 
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cream3.14159 said:
… to get:
x = x0 + v0 + at2/2

When I use E - 0.5mv^2= V(x)

(it should of course be x = x0 + v0t + at2/2)

why are you using E - 0.5mv2 ? :confused:

this is a perfectly ordinary integral of (constant - 2ax)-1/2

show us what you get :smile:
 
Hi!

Thank you for the response. I solved it with someone's help. The mistake I was doing was to use 0.5mv2-m*a*x to replace E. However, using v0 and x0 instead of v and x in this expression works to give the desired result and also, one has to put t0 = 0.
 
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