Which best describes vibration?

A)the distance traveled per unit in time
B)the action of moving back and forth quickly and steadily
C)the distance between one compression and the compression next to it
D)the action of moving through a material or substance

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.