physics
posted by Anonymous .
A bead of mass m slides without friction on a vertical hoop of radius R . The bead moves under the combined action of gravity and a spring, with spring constant k , attached to the bottom of the hoop. Assume that the equilibrium (relaxed) length of the spring is R. The bead is released from rest at θ = 0 with a nonzero but negligible speed to the right. The bead starts on the top of the circle opposing gravitational pull of the earth
(a) What is the speed v of the bead when θ = 90∘ ? Express your answer in terms of m, R, k, and g.
(b) What is the magnitude of the force the hoop exerts on the bead when θ = 90∘ ? Express your answer in terms of m, R, k, and g.

Use this link it shows the question you are solving , but it has slightly different parameters ie the equilibrium of the spring. It show that you need
GPE + EPE = KE + GPE + EPE
ie TOP=SIDE. You can then rearrange this to get everything on one side except v (your speed). 
Use this link it shows the question you are solving , but it has slightly different parameters ie the equilibrium of the spring. It show that you need
GPE + EPE = KE + GPE + EPE
ie TOP=SIDE. You can then rearrange this to get everything on one side except v (your speed).
I cant post link so search on google for part b) What is the magnitude of the force the hoop exerts on the bead and look for the mit link 
Part b) is working forces. So you have centripetal acceleration = Nkx where kx is the spring force.
cent acc = mv^2/r so us a)to derive this. 
hey man can you tell the answer,, plzz help