Rock whirling in vertical circle

[nrc_8706]

a rock whirls in a vertical circle of radius 8m. acceleration of gravity 9.8m/s^2

what must the speed be to have tangential=radial acceleration when the string makes a 37 angle with respect to the vertical?

is it Wsinangel=ma

v=Wsinangle*r/m)^1/2 ?

 

[Fermat]

If W is mg, then yes.

v² = gr.sin@