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
You have two different mechanisms at play, *friction* (“grippiness”) and *adhesion* (basically, stickyness).
Water is actually relatively sticky to the right substances, because water molecules are relatively strongly attracted to each other due to how the electrons are distributed in them. As a result, a bit of water helps your fingers stick to the page or the bag.
When it comes to grip though, you’re not looking for adhesion – it would be useful for keeping your car from being pulled *up* off the road, but that’s rarely something you need to worry about. Instead, you want your car tires to not slide – which they do by having unevenness on them which interlocks with the unevenness on the ground. Water smooths out that unevenness, which reduces grip.
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