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This Week in Berkshire History
Nov. 13, 1999: Jordan’s Furniture acquired in an all-cash transaction.
Charlie’s Corner: Mental Models
Mental Models: Physics/Friction; Economics/Trade-offs
Note: The primary mental models are listed above, and I explore those and secondary models below.
The annual, largely mindless, chore of leaf blowing my yard led me to think about friction and its ability to both help and hinder.
Starting with the physics, friction is a force that opposes relative motion between surfaces, or between layers of a fluid like water or air. On a microscopic scale, little bumps or irregularities in a surface “grab” onto each other as they pass, converting some kinetic energy into heat and/or sound (which becomes heat). Enter the leaf blower.
A leaf blower moves leaves by concentrating a large volume of air into one place, sweeping along leaves and other debris in its wake. But it’s not just the air coming from the nozzle that does the work. Friction between the air coming out of the blower and the surrounding air causes something known as entrainment that drags the surrounding air molecules along with it. Here’s a YouTube video demonstrating it.
Of course, friction is useful in all sorts of other ways, such as keeping our feet from slipping on the floor and our car tires gripping the road. On the other hand, friction causes tires to wear down and parts to wear out. It’s the price we pay for movement.
Friction is useful in human endeavors, too. Branches of government slow lawmaking, allowing time for debate (at least in theory). Judges and juries take time to deliberate before making decisions. These are points of friction deliberately introduced into a system to make it better, on average. The cost is time in backlogged courts and red tape.
On the personal front, we might introduce friction points such as leaving our phone in the other room to avoid the temptation of mindless scrolling. Or we might look to remove friction by laying out our clothes the night before so there’s no excuse for avoiding that workout.
We can’t eliminate friction, but we can choose where to put it.
Primary Models:
Physics/Friction: A force that opposes relative motion between surfaces or between layers of a fluid. This is relatively straightforward and intuitive in our daily lives when we see wear and tear on physical objects around us as the cost of our feet or tires not slipping.
Economics/Trade-offs: The benefits of friction come with a cost. Harder tires might wear more slowly but come at the cost of less stopping power. A thorough and dutiful judge or jury might get it right but at the cost of time.
Secondary Models:
Physics/Thermodynamics: Friction converts kinetic energy into heat (1st law: energy is conserved) that can’t be turned back into useful motion (2nd law: entropy increases).
Engineering/Damping: Checks and balances slow or stop oscillations and overreactions. Engineers build damping systems into things like car suspension and bridges to dissipate energy.
Psychology/Choice architecture: We can intentionally add friction to bad habits and remove friction from good habits.
That’s it for this week. Hit reply and let me know what you think. What have you been reading that’s worth sharing? Let me know in the comments.
Stay Rational!
Adam
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