Friction is a force that resists sliding motion between contacting surfaces. A bike, for example, has many instances of friction.
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Why do cats have rough tongues?
Cats have functional barbs or papillae on their tongue made of keratin, the same material that nails and our hair is made out of. They’re very rigid little barbs that face backwards.
How and why do our teeth fall out?
It’s normal and natural for baby teeth to fall out. Usually kids start to get loose teeth between ages 5 and 7. The new permanent tooth begins eating the root of the baby tooth away, that baby tooth becomes loose, and then the permanent tooth eventually pushes it out and erupts into its place.
How do the sun and rain make rainbows?
Rainbows are really cool because they’re a blend between art and science. It required a number of scientists to actually explain how they form, including Isaac Newton.
How do plants grow if there’s no sunlight?
Plants need sunlight for a process that we call photosynthesis. Plants are what we call autotrophs, meaning they create their own food or energy to grow.