physics
posted by Sasha on .
A boy throws a rock with an initial velocity of 2.47 m/s at 30.0 degrees above the horizontal. How long does it take for the rock to reach the maximum height of its trajectory?

Just do the vertical problem
Vi = 2.47 sin 30 = 1.23 m/s
v = Vi  4.9 t
at top, v = 0
0 = 1.23  4.9 t
solve for t