Chapter 9, Problem 70PP

The Spinning Eel. American eels are freshwater fish with long, slender bodies that we can treat as a uniform cylinder 1.0 m long and 10 cm in diameter. An eel compensates for its small Jaw and teeth by holding onto prey with its mouth and then rapidly spinning its body around its long axis to tear off a piece of flesh. Eels have been recorded to spin at up to 14 rev/s when feeding in this way. Although this feeding method is energetically costly, it allows the eel to feed on larger prey than it otherwise could.

70. A field researcher uses the slow-motion feature on her phone’s camera to shoot a video of an eel spinning at its maximum rate. The camera records at 120 frames per second. Through what angle does the eel rotate from one frame to the next?

1. A.    1°
2. B.     10°
3. C.     22°
4. D.    42°