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Re: [Phys-l] Laws of motion with constant acceleration (was projectile motion)



e.g. (not the only method)


x = v * t definition

dx/dt = d(v)/dt * t + v * dt/dt

v = a * t + v (0)

dx/dt = a * t + v(0)

dx = a * t dt + v(0) dt

x- x(0) = (a/2 ) * t^2 + v(0) * t

Of course, a bit more complex if v and or a are not appropriately constant.

bc was mistakenly thinking of dynamical problems, e.g. m*A + k | V| ^ (n-1)] * V +f (x) = F(x,t) where N-2 is the one equation.



On 2009, Nov 16, , at 14:46, David Willey wrote:

Bernard Cleyet wrote.....
Curious I thought there was only one -- from which all others (simple
ones not requiring Hamilton's principle, etc.) are derived.

I thought there were 2 (How can you derive anything from just 1?)

The definition of acceleration
a = (V - Vo)/t

and that distance traveled = average velocity × time
i.e. (x - xo) = {(V + Vo)/2}× t
noting average velocity is equal to the average of the initial and final
velocities if the acceleration is constant,

cheers,
David

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