Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a person standing up, the gauge pressure of the blood at the heart is of mercury. Find it, in mm of mercury, at the feet, below the heart, and at the head, above it. (Blood ; of mercury ; .)
Pressure is force per unit area, , in pascal. Below the surface of a liquid, ; the gauge pressure is . Pascal's law: a change of pressure in an enclosed fluid reaches every part of it, so a hydraulic machine gives .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Feet. of mercury, so .
Step 2. Head. , so .
Answer: About at the feet and at the head.
Check. That is why blood pressure is measured on the arm, level with the heart.
Watch out. Use the blood's density, not mercury's, for the column of blood.
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