Measuring wind speed with ball and string Newtons 2nd law

[eboarder2020]

hello everyone,

Im new to this forum but i really need some help doing a physics assignment. I am trying to use Newtons second law and the equation for wind resistance(click link) to determine the the angle made by a specific velocity. The link to the assignment is http://www.instruction.greenriver.edu/physics/anarayanan/PHYS201Sp2006/Notes/Essay2-201.pdf" . I've tried two different approaches but I am not sure if those are correct.

First, I did draw my free body diagrams and broke them up into components of x and y axis: Here is what I got

x(axis)=(wind resistance)-(m)(g)sin(theta)
y(axis)=(Force of tension)-(m)(g)cos(theta)

From there I've tried to manipulate both equations by solving for m, or g, and plugging into the other equation and solving for theta but thus far I've gotten non-realistic solutions.

So I thought maybe I was doing this a little to complicated, so instead I tried to solve this as if it were a triangle. I know that FT=mass*gravity if the ball is straight up and down. i also can calculate the force of windspeed using the formula, and then from there use some law of sins to get me an angle from the triangle but I am not sure if that's applicable in this scenerio.

Any and all help is much appreciated and thanks in advance

 

[andrevdh]

The ball is experiencing three forces, the tension $$T$$ in the string which works along the direction of the string, The weight of the ball $$W$$ vertically downwards and the drag $$R$$ acting horizontally on the ball in the direction of the wind. Taking the x-axis horizontally in the direction of the wind and the y-axis vertically upwards the tension in the string will contribute a x- and y-component to the equations, since it is working at an angle w.r.t. this x/y axis system. What are these two components and their signs in this system?

 

[eboarder2020]

Hey i turned in the assignment... I asked a few friends at school for help and I got it... The angle theta can be measured in the inverse tangent of the wind force over the mass times gravity. THanks for the help

 

[dav2008]

References: 1] http://en.wikipedia.org/wiki/Beaufort_scale
2] http://en.wikipedia.org/wiki/Saffir-Simpson_Hurricane_Scale

Oh my!

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[andrevdh]

Did they explain it to you? If not let's hope they are not there when you write exam.