The cat sat on the mat!

Chris Creagh's picture

What does this mean? In the blurb that goes with the video Spring Constants I state that “the phrase contains more meaning than the individual words” so what information can we glean from the phrase “The cat sat on the mat!”?

1) The cat is alive because it did something – it sat.

2) The cat and the mat exist at the same time in the same place.

3) Both cat and mat are in a gravitational field otherwise “sat on” has no meaning because there would be no up and no down.

4) The mat is probably on a solid surface because the weight force of the cat is balanced by a reaction force of the mat. The word “sat” implies a situation of equilibrium. The reaction force could be supplied if the mat was stiff and suspended in some way, like the seat of a swing, but it is more likely to be a flexible mat on the floor – as is the nature of mats.

5) The exclamation at the end means that this is more than a statement of fact, that there is some level of surprise about the cat sitting in the mat. Perhaps the cat did not previously like the mat; it was uncomfortable, smelled bad, had belonged to a dog. Perhaps it was an expensive mat and the cat should not be sitting on it, but what does a cat care about money? Perhaps the mat was covering a trap.

To get back to physics there are phrases that experts use to be concise and precise in their conversation and students have to learn what these phrases really mean for them to fully understand and take part in the conversation.

Rob Phillips's picture

That's a nice example, but does it only apply in Newtonian Physics? 

How would the cat and the mat behave if they were moving at close to the speed of light relative to me?