The velocity along horizontal direction is calculated as, vx=
d
dt
(x) =
d
dt
(5t) =5ms−1 The velocity along vertical direction is calculated as, vy=
d
dt
(y) =
d
dt
(5×27t−5t3) =5×27−5×3t2 since, this is a case similar to projectile motion and velocity andacceleration are perpendicular, when vy=0 0=5×27−5×3t2 t2=9 t=3s