Oil Separates a 20-Mm-Diameter Rotating Shaft from Its 20

question 21

Multiple Choice

Oil separates a 20-mm-diameter rotating shaft from its 20.5-mm-diameter bearing. The bearing is 80 cm long and the shaft rotates at 2000 rpm. The velocity gradient at the bearing
Surface is nearest:

• A) 6840 m/s/m
• B) 7260 m/s/m s
• C) 8040 m/s/m
• D) 9406 m/s/m

---

Definitions:

Cremaster Muscle

Extension of abdominal muscles originating from the internal oblique muscles; in the male, raises the testicles; in the female, envelops the round ligament of the uterus.

Dartos Muscle

Layer of smooth muscle in the skin of the scrotum; contracts in response to lower temperature and relaxes in response to higher temperature; raises and lowers testes in the scrotum.

Epididymis

A coiled tube where sperm are stored and mature, located at the back of the testis.

Acrosome

Cap on the head of the spermatozoon, with hydrolytic enzymes that help the spermatozoon penetrate the ovum.