FYFD

Tag: friction

  • How Cats Drink

    How Cats Drink

    While humans use suction and dogs scoop water using their tongues*, cats use a dainty fluid mechanism to drink. Researchers used high-speed video to find that cats drink by touching the surface of their tongue to the water and drawing their tongue rapidly back into their mouth. Friction between their tongue and the water creates a fluid column about which the cat closes its jaw before gravity breaks off the column. They also built an artificial tongue to test different frequencies and found an optimal lapping frequency dependent upon the mass of the feline.

    *ETA: More recent research show that dogs actually use the same technique as cats, not a scooping method.

    (Image credit: P. Reis et al.)

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    Avalanche Disk

    In the Science Storms section of the Chicago Museum of Science and Industry, you’ll find the mesmerizing sight of an avalanche disk. This 20ft disk spins at a variable rate and angle, and, from the video, you can see that the glass beads simulating an avalanche on the disk move very much like a fluid even though they are not. This is what’s called a granular flow and it’s driven by gravity and friction between particles.