Which normal mode runs faster?

• The out of phase mode
• The in phase mode
• Both run at the same speed

Two masses joined by springs settle into a normal mode. What is happening?

• Each mass swings at its own private frequency
• Whole system in one pattern at one frequency
• Both masses sit still while the springs swing

Why does the out of phase mode run faster?

• The masses become heavier
• Coupling spring pulls more
• The outer springs go slack

You start the system in a mixture of both modes. What does the energy do?

• It vanishes at once
• It stays locked in one mass
• It sloshes back and forth between the masses

You displace both masses equally in the same direction and let go. What follows?

• Pure in phase motion at the slower frequency
• Pure out of phase motion at the faster frequency
• Both masses freeze at the release point

Any starting motion of the two masses can be written as a sum of the two normal modes.

Circle one:   True   False

You pull only one mass aside and release. What motion follows?

• Both modes excited, with energy beating across
• Pure in phase motion only
• No motion at all

Kim watches one mode and says each mass swings at its own frequency. What is wrong?

• Modes only exist with damping
• Frequency belongs to the whole pattern, not each mass
• In phase motion has no frequency