Majority of the responding candidates got the initial speed but many of them could not determine the speed (u) at the maximum height reached because ux = 50ms-1 was wrongly substituted. Candidates failed to realize that at the maximum height the horizontal component of the projectile equal that of its initial velocity since ? = 0. Hence they could not establish the correct relationship between initial velocity (u) and ux.
The expected answers are:
(a) Let u represent the initial velocity of particle and ux the horizontal
component.
ux = u cos 30o = 50
u = 50
cos 30
= 57.7 ms-1
(b) Let v represent its velocity at the maximum height. ALTERNATIVELY
At the maximum height
v = vvx2 + vy2
vy = 0
vx = ux
= 50ms-1 = v 502 + 02
= 50ms-1