And Now a Word from Our Sponsor: Physics

It’s a darn good thing that there is no such thing as the “Daily Prompt Police” for I surely do not follow the rules. Today is no different.

As much as I’d like to piss and moan and whine and wail about the school subjects that confounded me and confound me still, instead I will post a video from my Physics course. We were asked to identify and discuss all of the physics concepts introduced in the course material. You most likely have seen this Honda ad, but it had escaped my viewing. I watched it at least a dozen times, not only for the assignment, but for the sheer enjoyment.

Below is the answer to the assignment.

Gotta love a good Rube Goldberg (see photo below) contraption! And from what I read about the making of the 2-minute Honda “Cog” commercial, the 606th take was the keeper. Of course designers worked out the contraption on paper first, applying all of the scalar and vector quantities involved in physics. In first draft, the calculations looked good, but as one article mentioned, sometimes variables such as changing atmospheric pressure and the build-up of dust were enough to throw off an otherwise perfect system.

Center of Mass: The use of this principle was most evident at two points: when the tires roll UP the ramp, and when the rear hatch closes on the car. According to internet searches, the tires have weights strategically mounted so that when the tires roll, the center of balance is changed by the weight and this propels the tire forward. The rear hatch closing alters the center of balance just enough to tip the front end of the car down and allowing it to roll off the ramp.

Projectile motion. This is a result of motion in two directions – forward by inertia and downward by gravity. The muffler (more center of mass principle applied here, too) strikes a system that launches a bolt or lug nut and it also traces a parabola as it follows the projectile motion principle.

The muffler is set in motion by the following system: a nut or bolt falls at first along a crooked wire. It manages to traverse this kinked path due to its potential energy – the energy that is stored. At the end of the wire it falls free to the ground. The wire releases Elastic potential energy: energy stored in an object when deformed and released when allowed to return to its original shape. The movement of the wire strikes the muffler with enough force to send it on its way.

Newton’s First Law:

Every body continues in a state of rest or of uniform velocity in a straight line unless an external force acts on it. Each of Newton’s laws is in effect along the entire system. The first law is illustrated by bodies are in motion: beginning with a cog as it rolls down a slightly inclined wooden rail. It has kinetic energy as it is in motion. It is slowing down as it rolls, due to the force of kinetic friction from contact with the wood. Some of the energy loss is mitigated by the incline, and vertical force of gravity. It hits a larger cog in a state of rest and stops moving. The energy has been transferred to the larger cog enough to overcome static friction and it starts to move along the rail.

The concept of Inertia, the tendency of an object to remain at rest if it is already at rest, or to keep moving if it is already moving, is also utilized along the entire system. It is most evident by the items that are still until they are somehow compelled to move by other forces acting on them.

Action at a distance forces: Forces which result even when the two interacting objects are not in physical contact with each other. They are able to exert a push or pull despite their physical separation e.g.: Gravitational forces; Electrical forces Magnetic forces.

It would seem to go without saying: the force of gravity is in effect along the entire system. However, in some of the stages, it is more apparent than others when specific use is made of the force such as in projectile motion and free fall.

Electrical forces are used to fire up the engine fan, those rather freaky walking wiper blades and the sound system. The speakers (wow, that many in one car?) use magnets to generate sound.

Also in play along the system are the contact forces: forces that arise when two objects are in contact. They include Normal Forces, Tension Forces, and Friction Forces.

Anywhere along the system where one body is in contact with another, the Normal Force is in effect. It’s just not all that evident. It factors into the calculation of inclines and friction. A tension force is transmitted through a string, rope, cable or wire. It is a pulling force, always directed along the rope, cable, wire or string. This force is employed when the last tire on the ramp falls and launches a pulley-type configuration where the downward pull of a wire that runs over a higher point creates an upward pull on the car seats beyond, opening them up.

Friction force: A force exerted by a surface as an object moves across it or makes an effort to move across it. As described above, the start of the system has a cog moving along and being slowed down by Kinetic (sliding) friction as a result of the contact between the moving cog and the wooden rail. When the first cog strikes the second, enough energy is transferred to the larger cog to overcome static friction: friction that resists a force that is trying to slide the surfaces across each other.

Second Law

When an external, unbalanced force acts on an object, the object will accelerate in the same direction as the force. The acceleration varies directly as the force and inversely as the mass.” This law is apparent starting with the first cog striking the second. The second moves or accelerates in the same direction as the first but with a different velocity due to its larger mass.

Third Law

“For every action force, there is an equal and opposite reaction force.” While this law is also in play along the entire system it is not always apparent. Those freaky wiper blades, though, are handy to describe this law. The water on the windshield triggers an electronic sensor that starts the wiper mechanism. The blades “wipe” the floor, pressing down. But since the mechanism is not fixed, the resulting equal and opposite force causes the wiper mechanism to push forward and the entire assembly “walks.”

 

Rube Goldberg Machine – click thru, if you wish, to see what Wikipedia has to say.

PS. This image reminds me… I used to play a computer game called Contraption. I told myself it was educational.

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Categories: Continuing Education

Tags: daily post, daily prompt, Laws of Physics

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