My son suggests that there ought to be a seventh "simple machine" added to the usual six; which is the Spring.
The standard six are:
1. Lever.
2. Inclined Plane
3. Wedge
4. Wheel, and axle
5. Pulley
6. Screw
These are distinguished on the basic of their basic function - each does something distinct in mechanical terms.
We could perhaps add "spring" for two reasons. Firstly because a spring does something (i.e. stores energy) that the other machines don't; and secondly because a spring is (or can be) simple.
Therefore it could be argued that a spring is also a simple machine.
Makes sense to me; albeit I suppose a spring isn't actually doing anything in terms of mechanisms; rather enabling something to be done in future.
More exactly; a spring does not fit the definition of a machine, in terms of a machine being something that changes the direction or magnitude of a force.
On the other hand; by a common sense understanding of what constitutes "a machine"; the spring does seem to be an appropriate addition.
(As nearly always; answers depend on assumptions: on prior definitions and exclusions.)
BTW - Such simple machines can be used (with intelligence and planning, and some joinery ability) to accomplish the apparently impossible... Such as quickly (within minutes) moving a 439 pound box containing fragile precision machinery, from the back of a van down steps into a basement, equipped only with the strength of a single 13 year old boy...
11 comments:
I can't say if the spring qualifies as a simple machine; however, I can say this -- I use the other six on an almost daily basis when working around the house and would be nowhere without them because I do most of the work alone.
These simple machines multiply force in exchange of increasing the distance the force has to be applied through.
You can do something analogous with a spring in time. This is similar (and more intuitive) to a pendulum - i.e a child on a swing. A little force applied each swing, adds more and more energy to the system which could then be a lot of force applied very quickly if it ran into something near the bottom of the swing.
@HS - Interesting perspective
@Frank - Simple machines are like a superpower.
OT but. My initial thought was, I wonder what he makes of bond graphs? Their invention strikes me as a rather good (and positive) example of the transition to a more abstract form of thinking that bedevils and enchants us poor moderns.
Short pdf by the inventor here: https://sites.utexas.edu/longoria/files/2020/10/Birth_of_-Bond_Graphs.pdf
A bow is a spring, more or less, and I think the bow form would have been the most prominent primitive and ancient application of this machine. There was a recent paper that made the argument that bow construction is so ubiquitous and so easily regained after loss despite the apparent lack of intermediary weapons, that it should be regarded not as an invention but as an instinctual human behavior.
It’s one of the three components of a (second order linear) dynamic system - mass, spring, and dashpot. Think of a car suspension or a sprint door. The electrical equivalents are inductor, capacitor, and resistor, the “LCR” circuit. These elements are qualitatively different from simple machines, but it’s an interesting question, isn’t it?
@Joel - I agree that the bow is an excellent example of a spring.
But it is not ubiquitous, and does require somebody of sufficient intelligence and abstracting ability to invent it - after all chimpanzees don't have bows.
The exception I am aware of is Australian Aborigines. Their culture is broadly similar (except in its religion) to the Bushmen of the Kalahari - but the Kung San have bows (and rely on them a good deal, with poisoned arrows) whereas Aborigines do not.
@Brent - You've thought about this more than me (I had to look up dashpot - I knew what it was, but not the name).
Your analogy with electrical components reminds me that I could "model" electricity only in terms of analogies with physical systems, especially fluids (e.g. voltage = height of drop in a water-wheel or turbine; current = the volume of flow. Such simple modelling got me an A Grade at A-Level Physics (a rare achievement in the 1970s!), without studying Maths beyond age 16 - so it worked pretty well. But I would have come up against a wall had I tried to take the subject further.
I thought there already was. Maybe its America vs Britain, but in college physics back in the 00s I remember the spring being in there.
@george - My son will be glad to hear it. Maybe you should edit the Wikipedia entry?
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