Standing Waves and Harmonics Pt2

Question 1

Free Boundary?

Answer 1

A free boundary is one that can freely move. This allows the wave to maintain its velocity and reflect back on the boundary maintaining its phase due to newtons 1st law that states that an object in motion will stay in motion unless/until acted upon by an external force.

Question 2

Fixed Boundary?

Answer 2

A fixed boundary is one that is fixed and rigid and does not allow the wave to maintain its velocity and phase. As a result of newtons third law which states that every action has an equal and opposite reaction, the wave gets inverted.

Question 3

What are two forms of graphical representations for longitudinal standing waves?

Answer 3

• Particle Displacement
• Pressure

Question 4

Relation between pressure and particle displacement:

Answer 4

They are inversely proportional so a pressure node will be a particle displacement antinode, vice versa.

Question 5

Open Ended Air columns Standing waves:

Answer 5

• The end of pipe are always pressure nodes because atmospheric pressure is unchanged
• The end of pipe are always displacement antinodes
• Equations are same as standing waves in a string