Question

5 masses are arranged in ascending order of mass from left to right, each mass is suspended between 2 springs vertically from a fixed wooden frame. By pushing up and down on a plastic lever at the bottom of the frame, the frame can be vertically shaken.

If pushing down on the lever 18 times in 10 second intervals causes the middle mass to swing vertically with a large amplitude, how frequently would you have to push down on the lever to excite each of the other masses of the frame? You can assume that the leftmost mass has a mass of m, the next has a mass of 2m, the middle has a mass of 3m, the fourth 4m, and the fifth 5m.

(sorry I was unable to post the picture to assist with this question).

Answer 1