Simple dynamics question, answer seems incorrect....

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    Dynamics Homework
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SUMMARY

The discussion centers on the interpretation of a dynamics problem involving tangential and normal acceleration. The key equations referenced are f = m*a and V = Vg*cos θ. The participant argues that the given velocity of 15 ft/s should be considered as the tangential speed, not merely a component in the y-direction. The conclusion drawn is that the use of Vg as V in the normal acceleration equation is incorrect, emphasizing the need for clarity in problem statements.

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  • Understanding of Newton's second law (f = m*a)
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  • Basic trigonometry, specifically cosine functions
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Homework Statement


H7virgC.png


Homework Equations


f=m*a
V= Vg*cos θ

The Attempt at a Solution


Is this solution correct. I did everything the same, but I did not use the 15 ft/s.
Since An= (v^2/ρ) with V being the velocity in the t direction. The 15 ft/s according to me is only the component of V that is in the y direction of a normall x-y plane.
So to get the velocity in the tangential direction of the path, so the full V. You need to do 15 ft/s / cos θ?
That they use Vg as V in the equation for An is wrong?
 
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Apparently the 15 ft/s given in the problem is meant to be the tangential speed. "Downward" is just meant to indicate that the boy is "swinging down" at this instant.

I understand how you interpreted it, and you would be correct for your interpretation. The wording of the statement of the problem could have been better.
 
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