wa the pic make ppl strain eyes
anyway,
Taking g = 10m/s²,
By the principle of conservation of energy,
change in KE = change in PE
½ mv² = mgh
½ (8)² = 10h
32 = 10h
h = 3.2 m
someone check my ans cos might be wrong, haven touch energy for quite long liao
using v^2 = u^2 + 2as
a = 10
v = 8
u = 0
so s = v^2 / 2a (darkie's formula)
you get answer = 3.2m
Alternatively, you can also use wishboy's method of COE