Saturday, October 24, 2020

Squirrel vs. Bird Feeder: Why the Squirrel Always Fails



No squirrels were harmed in the invention of these bird feeders. 
   

 Squirrels get hungry, like any animal, but these creatures are known to gather food from any source they can find. Even if that food is not meant for squirrels, such as birdfeed. That is why some companies invented bird feeders that prevent squirrels from stealing the food through a weighted motor that spins when the weight of a squirrel sets it off, like the one pictured above. The circular motion of their spin is controlled by physics!

    Centrifugal force is one aspect acting on the squirrel that pushes the squirrel away from the center of the feeder. This force is what helps to knock off the squirrel from the feeder as the rotational motion increases. Rhett Allain likes to think of this force as a "fake force" acting in the direction opposite the center of the circle. Whereas centripetal acceleration works to accelerate the squirrel in a circular motion by accelerating towards the center of the circle. Once the centripetal force gets too high, the squirrel is thrown off in a tangential path to the motion of the circle. 


    The motion of the squirrel was studied by Rhett Allain through the use of Tracker. He discovered that the squirrel takes 0.5 s per revolution which helped him to calculate an angular velocity of 12.6 rad/s. The radius of the birdfeed is 0.15 m. He was able to put these values together in order to calculate the centripetal acceleration of the squirrel, which he determined to be 23.7 m/s^2. 

Imagine being such a small creature that is forced to endure such speed and force in order to save the humans the struggle of purchasing more feed for wild birds. 


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