Question

Pressure that will be built in paint gun if stream of liquid paint flows out of it velocity of 25m/s

Answer 1

Well there isn't much to work with here so I would assume that initially the paint has only pressure head which turns into velocity head when the pain comes out (Bernoulli’s principal). So

Pressure= velocity^2 *density/2

= 25*25*400

=250 k Pa above atmospheric.