plot(T1, s1, 'r', T2, s2, 'g')
This presumes that T1 and T2 are each vectors of times after their calculation. But if so, if they are vectors, then you probably need to change your s equations slightly:
s1 = (V1f.*T1) -(.5*U*G*T1.^2);
s2 = (V2f.*T2) -(.5*U*G*T2.^2);
Best Answer