Question
The aqueous humor in a person’s eye is exerting a force of 0.300 N on the area of the cornea. (a) What pressure is this in mm Hg? (b) Is this value within the normal range for pressures in the eye?
Final Answer
- Normal eye pressure is 12 - 22 mm Hg. Yes, this pressure is within the range of normal. Eye pressure is an important measurement during an eye exam since high pressure could indicate conditions such as glaucoma.
Solution video
OpenStax College Physics for AP® Courses, Chapter 11, Problem 18 (Problems & Exercises)
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Video Transcript
This is College Physics Answers with Shaun Dychko. The Aqueous humour in a person's eye exerts a force of 0.300 newtons on an area of 1.10 centimeter squared and we are trying to figure out what is the pressure is in that case. So pressure is the force divided by the area but the area's going to need to be converted into meters squared in order to have mks units since we are mixing this quantity with the newtons; newtons is a mks unit so we want everything else to be mks units as well. So we have 1.10 centimeter squared times 1 meter for every 100 centimeters and we multiply twice to get rid of the centimeter squared here and we end up with 1.1 times 10 to the minus 4 meter squared. Okay! So we have this force then divided by this area gives us 2.7273 times 10 to the 3 pascals and then we multiply by 1 millimeter of mercury (Hg) for every 133 pascals and the question asks us for the answer in millimeters of mercury so we have to multiply by this conversion factor and that gives us 20.5 mm Hg. And with a quick internet search, I found that normal eye pressure is from 12 to 22 mm Hg and so yes, this pressure is within the range of normal.