The coordinates of a moving particle at any time are given by x=a t2 and y=b t2. The speed of the particle at any moment is
2t√(a2+b2)
Velocity along X-axis Vx=dxdt=2at
Velocity along Y-axis Vy=dydt=2bt
Magnitude of velocity of the particle,
v=√vx2+vy2=2t√a2+b2