The computation of the actual velocity is shown below:
Because the path of its paddles is opposed to the current direction, the real velocity can be determined by deducting the current velocity to its velocity while paddling
So, the actual velocity is
= Upstream - downstream
= 19 km/hr - 15 km/hr
= 4 km/hr
As we can see it is in positive, so it is an upstream direction
Flux=q/e0 e0=8.85*10^-12 !!! Cube has 6 sides, so flux through one side is equal to total flux/6 Ans=9.11*10^(-6)/((8.85*10(-12))*6)=(approximately)1.72*10^5Nm^2/C
