- #1
drofenaz
- 7
- 0
Homework Statement
Derive the expressions for the [itex]i_r[/itex] and [itex]i_θ[/itex] components of velocity and acceleration.
Homework Equations
[itex]r=|r|i_r[/itex]
[itex]\omega=\frac{dr}{dt}[/itex]
[itex]\alpha=\frac{dω}{dt}=\frac{d^2r}{dt}[/itex]
The Attempt at a Solution
[itex]r=|r|i_r[/itex]
[itex]\omega=\frac{dr}{dt}i_r+r\frac{di_r}{dt}[/itex]
[itex]\alpha=\frac{d^2r}{dt^2}i_r+\frac{dr}{dt}\frac{di_r}{dt}+\frac{d^2i_r}{dt^2}r+\frac{di_r}{dt}\frac{dr}{dt}[/itex]
4. The solutions I need to get to
[itex]\omega=\frac{dr}{dt}i_r+r\frac{d_\theta}{dt}i_θ[/itex]
[itex]\alpha=\frac{d^2r}{dt^2}i_r+\frac{dr}{dt}\frac{di_\theta}{dt}i_\theta+\frac{dr}{dt} \frac{d\theta}{dt}i_\theta+r\frac{d^2\theta}{dt^2}i_\theta-r\left(\frac{d\theta}{dt}\right)^2i_r[/itex]
5. Thoughts
I think that they're substituting in something for parts of my answer. I just don't know what they're substituting in, or how to find it.
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