I posted a the same problem with different numbers a minute ago. The answer to the problem below (same as the other with different numbers) is 28 degrees. Maybe this will help to solve it? Thanks!
A block is hung by a string from the inside roof of a van. When the van goes straight ahead at a speed of 28 m/s, the block hangs vertically down. But when the van maintains this same speed around an unbanked curve (radius = 150 m), the block swings toward the outside of the curve. Then the string makes an angle è with the vertical. Find è.