Centripetal acceleration and angles

[Bjamin0325]

Homework Statement

A block is hung by a string from the inside roof of a van. When the van goes straight ahead at a speed of 34 m/s, the block hangs vertically down. But when the van maintains this same speed around an unbanked curve (radius = 120 m), the block swings toward the outside of the curve. Then the string makes an angle theta with the vertical. Find theta.

Homework Equations

Fc=v^2/r

The Attempt at a Solution

All I could do was get the centripetal force, 34^2/120=9.63333N.

I have no idea where to go from here, and there are no similar problems I can find.

Thanks a million for any help.

 

[andrevdh]

The formula that you give is for the acceleration. So you calculated the centripetal acceleration.

The block will experience two forces - its weight, W, and the tension T in the string. The vertical component of the tension balances the weight of the block while the horizontal component supplies the necessary centripetal force.