Obtaining kinetic energy equation.

AI Thread Summary
The discussion revolves around deriving the kinetic energy equation for a mass represented by a specific position function. The user seeks clarification on whether it's valid to sum the velocities in the x and y directions to find the speed for the kinetic energy formula. The response emphasizes that velocities cannot be simply summed; instead, Pythagoras' theorem should be applied to calculate the resultant velocity. Consequently, kinetic energies in the x and y directions can be calculated separately and then added together. This approach ensures accurate representation of the kinetic energy based on the mass's motion.
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The question is about 2 sticks standing above each other, but i have a more general question.

The position of my mass is described by: (2rsin(a) - rsin(b) , 2rcos(a)+rcos(b))

the goal is to get a formula for the kinetic energy, so i need the speed of the mass.

If i take the derivatives of both functions i get the speed in x and y direction.

So my question is: is it allowed for the v in (mv^2)/2 to summ up the velocities in both directions and to use it as the formula of v in the kinetic energy equationThis is my first post on this forum, so sorry for the lay-out of this question which is probably wrong...
 
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You can't just sum them, you have to use Pythagoras' theorem.
 
sk1105 said:
you have to use Pythagoras' theorem.
From which it follows that what you can do is calculate the KEs in the two directions separately and add those.
 

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