You always list out the 6 basic kinematic quantities:
$\displaystyle x_0 \ or \ y_0 = \text{Initial Position}$
$\displaystyle x_f \ or \ y_f = \text{Final Position}$
$\displaystyle v_{x0} \ or \ v_{y0} = \text{Initial Velocity}$
$\displaystyle v_{xf} \ or \ v_{yf} = \text{Final Velocity}$
$\displaystyle a_x \ or \ a_y = \text{Acceleration}$
$\displaystyle t = \text{Time}$
If you are missing more than 2 of these, your problem can't be solved using conventional kinematics equations.
After you list those six in their appropriate directions, then you add any other variables, equations, or relations.
Then you re-read the problem carefully, and see all the possible ways you could find the answer. Pick the one you think is the easiest and use it. If you are unsure about your answer, pick an alternative method and see if you get the same answer. If there are no alternative methods, just use your answer and try to generate something that is true that does not result from your answer.
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Last edited by Aryth; Sep 19th 2008 at 01:04 AM.
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