What do Van der Waals forces do?

weak electrostatic forces that attract neutral molecules to one another.

Explanation:

Van der Waals forces are weak electrostatic forces that attract neutral molecules to one another. Particles in liquid or air vibrate and move constantly. Thus, they collide with other particles, including the media's particles such as water molecules—the process known as Brownian motion (Figure 50).

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.