#### Answer

$F=858N$

#### Work Step by Step

We know that:
$\frac{dm}{dt}=\rho v A$
We plug in the known values to obtain:
$\frac{dm}{dt}=1000(20)\pi(0.02)^2=25.13Kg/s$
Now, $\Sigma F_y=\frac{dm}{dt}v(v_B-v)$
We plug in the known values to obtain:
$F=(25.13)(20sin 45-(-20))$
This simplifies to:
$F=858N$