4. A pipe has an initial radius of r1, which then changes to a radius of r2. The velocity of the water in the initial part of the pipe is v1. The segment of the pipe with the smaller radius is also 0.5 m higher than the initial pipe segment. What is the pressure difference between the two parts of the pipe? (6 pts) Let radius 1 = 0.07 meters and v1 = 0.25 m/s, while radius 2 = 0.01 meters (Ctrl) H