Ask Dr. Rob: Using the Force

So you wanted more \”Ask Dr. Rob.\”  Next you are going to be asking for a colonoscopy.
Well, I guess I can do it.  It has been a long time since I have done one of these.  I thought I was being merciful.  Whatever.

Here\’s a question from a moderately fictional person named Mike:

Dr. Rob:

What\’s the deal with physics?  I heard that you have to take physics class to get into medical school.  As a doctor, do you ever use physics?


Moderately Fictional Mike.

Wow, what a coincidence!  That\’s the question I would have chosen had I written it myself!  What\’s the chance of that?

To answer your question: yes, I do use physics quite a bit.  It\’s a good thing, because my dad is a physicist.  This is a physical world we live in, with irresistible forces impersonally shoving us around without getting permission.  My father never told me about this dark side of the forces.

Force #1: Gravity

The first example of these forces at work is the ingrown toenail.  Toenails ingrow for one reason: they can\’t grow out.  Instead of sticking out the front of the toe like any self-respecting toenail would do, they grow into the toe.  Why do they do this?  What causes some toenails to grow in while the others behave respectably?


Ever since Sir Isaac Newton suffered a head injury, gravity was felt to be related to the mass of an object.  The bigger the object, the bigger the gravity.  But then came Albert Einstein, and the trouble began.  Einstein\’s theory of general relativity put forth the idea that gravity wasn\’t even a force, but instead a curvature of the spacetime continuum.  Wikipedia explains:

Einstein discovered the field equations of general relativity, which relate the presence of matter and the curvature of spacetime and are named after him. The Einstein field equations are a set of 10 simultaneousnon-lineardifferential equations. The solutions of the field equations are the components of the metric tensor of spacetime. A metric tensor describes a geometry of spacetime. The geodesic paths for a spacetime are calculated from the metric tensor.

Confused?  Yeah, well so is everyone else including the toes. What started out with a simple equation in Newtonian Physics:


became 10 simultaneous, nonlinear, differential equations! Yuck!!

Despite his lifelong battle with fruit, Newton remained
a gentle soul.

To get back at Einstein, the toes decided to take advantage of these changes.  Using a loophole in this new law, they increased the local gravity in his big toes, pulling the nail down into the flesh part, giving Albert the first ingrown nail in recorded history.  In foot-wracking pain, Einstein tried to recant his theory, but the damage was done.  This is why the presence of an ingrown toenail, which is evidence of a hyper-gravitational podiatric state, is invariably accompanied by the following:

  • People step on them – scientists have proven that a foot with an ingrown nail is 10 times more likely to be stepped on than those without.
  • Heavy objects are kicked – careful analysis has shown that objects such as coffee tables, lamps, and even large appliances move into the path of a person with an ingrown nail.

Why do these things happen?  Gravity.  Thanks a lot, Albert!

Einstein, on the other hand, was left embittered by
his chronic foot pain

Force #2: Opposing Forces

Following his head injury, Sir Isaac Newton (yeah, him again) decided to take the law into his own hands.   The result of this was the creation of Newton\’s Laws of Motion.  His design was to prevent future fruit-related head injuries, and he was largely successful (except for one unfortunate Kumquat encounter).

Kumquats can be dangerous

Newton clearly had a lot more sense than Einstein, and he kept his toenails happier as well.  Take it from me: always keep your toenails happy.  The three laws that Newton made were about moving objects, the most famous of which was the 2nd law, with the formula:


Translated: Force = Mass x Acceleration.  This is a great formula because it is so simple (as opposed to Einstein\’s ten differential equations), but sadly, it doesn\’t apply in the doctor\’s office.  The third law (the law of reciprocal actions) however, applies very nicely:


Which translates: \”any force that is applied to object 1 due to the action of object 2 is automatically accompanied by a force applied to object 2 due to the action of object 1.\” (1)

The application in medicine is not in the clinical realm, but in the interaction between doctors and nurses.  Since both doctors and nurses are important cogs in the machine of medicine, they commonly have significant effects on each other.  Believe it or not, they don\’t always agree.  I am sorry if I shattered anyone\’s image of a blissful cooperation and camaraderie.  That is true most of the time (if by \”most\” you mean \”almost never\”).   The Law of Medical Opposing Forces goes like this:

Any force that is applied on a nurse by a doctor is automatically accompanied by an opposing force applied by the nurse on the doctor.

The best example goes something like this:

Nurse: Doctor, Mr. Tucker\’s wife wants to talk to you about the side effects of all of the 29 medications you prescribed.  I told her you were on the floor, so she\’s expecting you

Doctor: Fine, nurse, I\’ll do that.  Let me first write these three orders for enemas and the order to discontinue the sedative for the screaming lady in room 244.

Nurse: That\’s nice.  Did I tell you that the Mr. Wafter has a large abscess that started draining?  I left it alone after explaining to him that you are an expert at wounds like that.  His roommate had to be moved, though, because he couldn\’t take the smell.

Doctor: Wonderful.  I forgot to mention that I can\’t discharge Mr. Whiner or Mrs. Screamer today.  I just want to wait another day to make sure they are stable.

Nurse: I\’ll be sure to have the night shift nurses call you hourly through the night to give you updates.

These two children are in training.
This picture was taken before the hand-to-hand combat

This is a very important law to understand, especially for doctors in their residency.  Most residents assume that they are in charge since they have those letters after their name, but what they don\’t realize is that they are weak forces.  Nearly all forces exerted by a resident on a nurse are met with much stronger opposing forces.

There are other opposing forces in healthcare, including surgical vs medical doctors, doctors and nurses vs hospital administrators, members of congress vs. people who don\’t get money from drug companies, and insurance companies against anyone trying to get money from them.  Anyone dealing with healthcare needs to understand this very important law of physics.


I am just scratching the surface (which, of course, involves the force of friction), but the spacetime continuum is putting force on me.  But the bottom line (x-axis) is that physics is at the center of the medical universe.

Here\’s to you, Dad.  May the force be with you.

4 thoughts on “Ask Dr. Rob: Using the Force”

  1. Wow, Dr. Rob it sounds like Physics is almost as useful to clinical medicine as Organic Chemistry!

    I think we should add another year or two to the length of medical education so future physicians can immerse themselves in this clinically vital knowledge.

    Thank you for exposing the absurdity and hilarity of whoever controls the MCAT.

  2. Wow, Dr. Rob it sounds like Physics is almost as useful to clinical medicine as Organic Chemistry!

    I think we should add another year or two to the length of medical education so future physicians can immerse themselves in this clinically vital knowledge.

    Thank you for exposing the absurdity and hilarity of whoever controls the MCAT.

  3. You know, I have asked myself the same question. While I would not claim to be competent in physicis (translate – forgot everything the second the final exam was over) calculus, too come to think of it – I think the arena of friction and resultant lubrication or redirection of force vectors is an area worthy of research.
    My real question – do physicists have to take Bio Chem?

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