Saturday, December 15, 2012

Slinky Physics

This is a perfect demonstration of where to look for Physics. Anywhere!
A simple question of “What if…” has led to a ‘front page’ article in the American Journal of Physics. I love it.
This is great for introducing the idea of cognitive dissonance. A student in a lecture or classroom will have misconceptions, show them this and that will flip their head around so that those misconceptions can no longer exist in their brains.
We can go further than this. After proving that all masses fall to the ground at the same acceleration, (think Galileo) demonstrating that it’s not like that in all cases by dropping a mass next to a slinky shows it’s not as simple as that. They’ll hit the ground at different times.*
What really gets me about this is that it holds true even if your drop a 10 foot pole. The top falls while the bottom of the pole waits for the information to get there before it moves. It just happens a lot fastest with a pole that a slinky.
*providing you are not dropping the mass from the same height as the centre of mass of the slinky.

Saturday, December 1, 2012

Physics hobbies part 1

Ranting about Physics ads 

Above roads around the place I have seen this ad. It claims that the New Lancer Whatever, can defy physics, or you yourself can defy physics when you drive it. Wow!

 This is a big call. Physics, a subsection of a larger field of research we call science, deals with the laws of the natural world. Let me mention a few of them here.

  1. Laws of Motion (Newton and Kepler) 
  2. Law of Gravity 
  3. Law of thermodynamics 
  4. Conservation of mass and energy (E=mc2) 
  5. Conservation of momentum 
  6. Photoelectric effect 

I would like to concentrate on the first one especially, as it is quite central to the whole idea of driving a car. The law of motion by that famous old alchemist (and general nut job!) Isaac Newton. Newton came up with three pretty revolutionary (at the time) ideas that changed the way we thought about the natural world and how things behaved in it. His three laws in brief were as follows.

  1. An object at rest, will continue to stay at rest until acted upon by an external unbalanced force. And, an object in motion will continue to stay in motion until acted upon by an external unbalanced force 
  2. F=ma 
  3. Every action has an equal and opposite reaction 

Pretty simple. Short and sweet. They seem obvious, but he was the first guy to write them down, and it changed everything. You can demonstrate Newtons three laws with any object you can find.

My coffee mug for example, is not moving, there is no external unbalanced force acting upon it, so it stays still. Until I pick it up. If it fell off the table, it would continue to fall off the table until something like the ground stops it from falling. (Newtons first law) When it is full, it is heavier, therefore, a little bit harder to move, the mass of the mug is bigger so the force I have to apply to it to move it os also bigger (Newtons second law). And when I punch something due to the fact that this ad defies nothing else but logic, my fist hurts as well (Newtons third law).

Even if you want to consider theories, not laws, Physics has some pretty well thought out theories. Quantum mechanics, special relativity, big bang etc .

It seems strange to me that the ad would want to champion the fact that the Lancer can defy physics. Which part of physics does it defy? Is it the thermodynamics part, cos that isn’t really relevant, same with Kepler’s laws, or Quantum mechanics. I can only assume they mean that you can defy the motion part, which seems very silly to me. Why would we want to go and defy all the good work that Newton did. 

Lets not go too far with defying all this physics anyway. Without Newtons three laws, this car would not have even be made. let alone having this so called amazing performance. We wouldn’t be dealing things like friction for example, accelerating wouldn’t make an sense and…aaaarrrrrrgh this friggin car wouldn’t have even been able to be assembled!

In conclusion, crap ad. Don’t buy this car, because its ad is ill informed. Why can’t it just say, this car drives good, or people will think your bits are huge if you drive this car, but don’t use physics cos you think it sounds smarter, that is poor form.

 If the car company can’t even get a simple physics slogan right, what kind of complex engineering vehicle can they possibly make? There are so many examples of bad ads that use Physics and Science poorly. This one is a particularly good example! What are your favourite bad ads?