So we all know how car tires are less grippy when it’s wet.
But why is it better to use water or saliva on my fingers when trying to open a plastic bag, or quickly turn paper pages over?
And why does applying washing soap/shower gel to my slippery yoga mat make it grippy again?
Does this means car tires would be grippier on a soapy surface? Is so do they apply this principle in (for example) motorsports?
Thanks in advance folks!
In: 3
Multiple reasons. First, your fingers are oily due to natural oils produced and excreted by your skin (called sebum). Sometimes they’re too oily and you’ll get better contact with a layer of water or saliva between your fingers and whatever you’re trying to grip. Second is your fingers are not flat – there’s lots of grooves on them. Adding a bit of liquid can increase the surface area (actually the surface tension) between your fingers and whatever you’re grabbing, especially if what you’re grabbing is porous (like paper). But the biggest reason is that a bit of water is pretty sticky due to surface tension holding the water molecules together like glue. Get a lot of water, and the surface tension breaks and the water becomes more of a lubricant than a glue, which is why tires will tend to spin and slide when roads are wet.
As for your yoga mat, sweat and oils from your body likely accumulate on it, and then dirt and dust adheres to that coating. When you wash it, you expose the grippier material refreshing the grip.
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