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Work and Kinetic Energy in two and three dimensions

Because of the vector nature of Newton's second law the expressions for work and kinetic energy which we derived for one dimensional motion can be extended to higher dimensional motion as well.

Consider first the case of motion with constant acceleration such as for example projectile motion. Now I have an equation such as tex2html_wrap_inline404 for each dimension:
eqnarray102
The conserved quantity analogous to energy in one-dimension is formed by adding these equations and multiplying by tex2html_wrap_inline406:
 eqnarray109
The last bracket is a scalar formed from the vectors tex2html_wrap_inline408 and tex2html_wrap_inline410. It can be shown that for arbitrary vectors
equation125
where tex2html_wrap_inline412 is the angle between vectors tex2html_wrap_inline414 and tex2html_wrap_inline416. Applying this piece of math to Eq. 26 we can write
equation132
where the expression for work in higher dimensions becomes
equation134




Collin Broholm
Wed Oct 1 11:41:36 EDT 1997