Why are the soles of our shoes designed jagged?

Question

It is said that the magnitude of frictional forces do not rely on the magnitude of area of a surface. Then,how does the jagged sole of our shoes play a role in balancing us?

Answer 1

You are correct, the jagged soles do not increase friction. Neither do the treads on tires. They are jagged because it prevents slipping on water. The cuts give water a place to go when you step in a puddle or a car drives over water. Thus, it's harder for a car or your foot to momentarily float on the puddle and slip. You'll notice that race cars normally use non-treaded tires (and these are designed to maximize friction), the cars only use treads when the track is wet.

By the way, good question. Some books will address this question in the text in anticipation of clever students asking it.

Response to E-mail:
Since your address doesn't seem to be working:

Honestly, I'm not exactly sure why race cars don't use treads, other than the fact that it shouldn't affect the frictional force, so why bother? You asked if jagged soles increase gripping force on dry surfaces, and based on all the physics I know of (I'm a graduate student in physics now), the answer is no. They might help us not to slip if the surface is dirty or dusty, because often people slip on dust if they're wearing smooth shoes. In this case the dust acts a lot like water would to cause slippage, and the treads give it a place to collect and increase the pressure on the floor so we don't slip. Technically, I don't think this increases the "friction". The word "gripping force" is colloquial, so I suppose you could say that it helps with that.

Answer 2

When you dig into an icy, mucky surface, you're pushing in a more perpendicular direction against the surfaces your cleats are in contact with. Friction mean a lot more when the force isn't parallel with the surface. You also have gravity working for you, since to slip when you're dug in your foot would have to be forced upward.

Answer 3

they create more friction (traction).

Answer 4

TRACTION
GOD BLESS