$2\mathrm{.}11$ Pressure and Hydrostatic Head

$3.$ An evaporator shows a reading of $40$kPa vacuum. What is the absolute pressure in the evaporator in kilopascals?

$4.$ A U$-$tube manometer filled with mercury is connected between two points in a pipeline. If the manometer reading is $26mmHg,$ calculate the pressure difference in kilopascals between the points when $($a$)$ water is flowing through the pipeline, and $($b$)$ air at atmospheric pressure and $20C$ with a density of $1\mathrm{.}20k\frac{g}{m^3}$ is flowing in the pipeline.

Thought Problems

When you lie motionless on a bed, the bed supports you with a force that exactly matches your weight, and when you do the same on the floor, the floor pushes