When a tuning fork vibrates over an open pipe and the air in the pipe st21 to vibrate, the vibrations in
the tube are caused by
a. resonance.
b. reinforcement.
c. harmonics.
d. beats.

Brutus, the dog, is pulling a bone to the left with a force of 20 n. lassie, another dog, is pulling a bone to the right with a force of 18n. what is the net force? a. b. c.

The direction of the current in an alternating current circuit remains constant. is direct. changes repeatedly. changes randomly.

Determine the moment of the force f about an axis extending between a and c. express the result as a cartesian vector. a is at the origin, c is at (4,3,0) and f = (4i + 12j -3k) lb coming out of b (4,3,-2).