Curvilinear Motion: Rectangular Components

  • Thread starter aaronfue
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  • #1
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Homework Statement



What is the magnitude of the velocity at t=4.00s?

I would like to see if my approach and answer is correct.

Homework Equations



Position: r = {-30cos([itex]\frac{\pi}{10}[/itex]t) i + 30sin([itex]\frac{\pi}{10}[/itex]t) j - (7t) k} ft


The Attempt at a Solution



I took the first derivative to get the velocity and my equation came out to be:

r' = {3[itex]\pi[/itex]sin([itex]\frac{\pi}{10}[/itex]t) i + 3[itex]\pi[/itex]cos([itex]\frac{\pi}{10}[/itex]t) j - (7) k} [itex]\frac{ft}{s}[/itex]

And after plugging in t=4, my velocity vector equation was: [(8.96)i + (2.91)j - (7)k] [itex]\frac{ft}{s}[/itex]

Then my velocity magnitude was: 11.74 [itex]\frac{ft}{s}[/itex]
 

Answers and Replies

  • #2
ehild
Homework Helper
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1,901
It is OK, but the result can not be accurate to four significant digits.

ehild
 

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