What is the Science connection?

[Denisec4502]

What is the science connection between "caterpillar tracks" made by an army tank and friction? My teacher has posed this question and I am stumped? Help.

[jake-the-peg]

Well this is quite interesting.

The obvious answer would be to say that a tank with caterpillar tracks has a larger contact with the ground than one with wheels and so there is more friction.

That would however be wrong.

Contrary to popular opinion (especially amoungst buy racers) Friction does not depend on the amount of surface area with the ground.

http://www.physlink.com/education/askexperts/a e140.cfm

What caterpillar track do in spreading the load over a wider area is to reduce the pressure on the ground which makes the vehicle less likely to sink into the ground.

So I suspect your teacher is being smart and has set this as a trick question expecting the wrong answer, or to see who goes to the bother of researching a question and who makes a knee jerk response

[MatydaLover]

It does seem a strange question. If the tracks were frictionless with regard to the road then the tank would make no progress; the tracks would slip.

But caterpillar tracks are no different from bicycle wheels or the soles of your shoes ** in that respect.

** or even the hands and knees of a crawling baby, or the stomach of a snake, or a nail in a block of wood, or ... ...

[Teddio]

A vehicle with caterpillar tracks has higher friction than a similar sized wheeled vehicle. It has the advantage however of better traction and lower pressure on the ground. Look up the Soviet Union's second world war tank, the T34.

[MatydaLover]

Another good reason for laying a track (although little to do with friction) is that a similar-sized wheeled-vehicle might be stopped by a ditch, but the tank would not.