Course:PHYS341/2019/pre-reading/Q5

For Quiz 5 on Feb. 11th.

Consider a pipe 34 cm long. Estimate the frequencies of the lowest three modes (using our most simple approximate model) in the following cases? Take the speed of sound to be 340 m/s.

1 Open at both ends

	(a) 250, 750, 1250 Hz.
	(b) 250, 500, 750 Hz.
	(c) 500, 1500, 2500 Hz.
	(d) 500, 1000, 1500 Hz.
	(e) 1000, 3000, 5000 Hz.
	(f) 1000, 2000, 3000 Hz.

2 Closed at both ends

	(a) 250, 750, 1250 Hz.
	(b) 250, 500, 750 Hz.
	(c) 500, 1500, 2500 Hz.
	(d) 500, 1000, 1500 Hz.
	(e) 1000, 3000, 5000 Hz.
	(f) 1000, 2000, 3000 Hz.

3 Open at one end, closed at the other

	(a) 250, 750, 1250 Hz.
	(b) 250, 500, 750 Hz.
	(c) 500, 1500, 2500 Hz.
	(d) 500, 1000, 1500 Hz.
	(e) 1000, 3000, 5000 Hz.
	(f) 1000, 2000, 3000 Hz.

4 Which case can be predicted most accurately?

	(a) Open-open.
	(b) Open-closed.
	(c) Closed-closed.

5 For the first mode of an open-closed pipe, where are the pressure and velocity ("vibration") nodes (may be approximate)? (See fig.12.3).

	(a) Pressure and velocity nodes at the open end.
	(b) Pressure and velocity nodes at the closed end.
	(c) Pressure node at the closed end, velocity node at the open end.
	(d) Pressure node at the open end, velocity node at the closed end.