We'll recall the fact that the impulse represents the change in momentum of an object.
I = F*delta t
F is the force applied to the object over the time interval delta t
But F = m*a => I = m*a*delta t
But a = delta v/delta t => I = m*delta v*delta t/delta t
I = m*delta v (1)
delta v = vf - vi
vf is the final speed of the object and vi is the initial speed of the object.
We'll plug into the equation (1) the given information:
4.1 = 0.21*(Vf - 0).
The initial speed is zero since the object is stationary, at first.
4.1 = 0.21*Vf => vf = 4.1/0.21
vf = 19.52 m/s
Therefore, the speed of the object, after the impact, is of 19.52 m/s.