Respuesta :

Using SUVAT (S is displacement, U is initial Velocity, V is final velocity, A is acceleration, t is time);
S = 80m
U = 0ms^-1
V = ?
A = 9.8ms^-2
T = XXX
Use S U and A to find V;
V^2=U^2+2AS
V^2=0+2*80*9.8
V^2=1568
V=39.6ms^-1