# Homework Help: Simple dynamics question, answer seems incorrect...

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1. Jul 14, 2016

### Pascal1p

1. The problem statement, all variables and given/known data

2. Relevant equations
f=m*a
V= Vg*cos θ

3. 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?

2. Jul 14, 2016

### TSny

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.