Angle a Block swings while a van turns?

[eatingblaa]

1. A block is hung by a string from the inside roof of a van. When the van goes straight ahead at a speed of 21.5 m/s, the block hangs vertically down. But when the van maintains this same speed around an unbanked curve (radius = 111 m), the block swings toward the outside of the curve. Then the string makes an angle x with the vertical. Find θ.



2. centripetal acceleration Ac = v^2 /r
normal force Fn= mg

i then worked out that the sin x = Ac/Fn

I think these should all be right



3. Ac = 4.164 N

And then sin x = Ac/Fn, but I have no idea where to go from here or even if I am on the right path

 

[tiny-tim]

Hi eatingblaa!

centripetal acceleration Ac = v^2 /r
normal force Fn= mg

i then worked out that the sin x = Ac/Fn

normal to what?

Hint: use Newton's second law (F = ma), in a particular direction.