Physics Mechanics Q1

Horizontal motion: 2.5 = [Va.cos(30)].t
where t is the time of flight
hence, t = 2.5/[Va.cos(30)]
Vertical motion: use s = ut + (1/2)at^2
with s = -(1-0.25) m = -0.75 m, u = Va.sin(30), a =-g(=-10 m/s^2), t = 2.5/[Va.cos(30)]
hence, -0.75 = Va.sin(30)[2.5/(Va.cos(30)] + (1/2).(-10).)[2.5/(Va.cos(30)]^2
solve for Va gives Va = 4.36 m/s

Repeat the above calculation for hroizontal distance of 4 m.