Q 1: If you connect a hoseto one end of a metal pipe and blow compressed air int

Question

Q 1:

If you connect a hoseto one end of a metal pipe and blow compressed air into it, thepipe

produces a musicaltone. If instead you blow compressed helium into the pipe at thesame

pressure andtemperature, will the pipe produce?

I. The sametone

II. A higher-pitchtone

III. Lower pitchtone

Explain thereason.

Q 2:

You are at an outdoorconcert with a wind blowing at 10m/s from the performerstowards

you. Is the sound youhear Doppler shifted? If so, is it shifted to lower orhigher

frequencies?

Q 3;

Which is the mostaccurate statement of Bernoulli s principle?

(I) Fast-moving aircauses lower pressure;

(II) Lower pressurecauses fast-moving air;

(III) Both (I) &(II) are equally accurate.

Explain your aboveselected answer as well.

Q 4:

Suppose you doubledthe mass of a clock‘s pendulum (including the rod and theweight

at the end) whilekeeping its dimensions the same. Would the clock run fast orslow?

Explanation / Answer

1) speed of sound is faster in He than in air v = f Since the length of pipe is fixed (like an organ pipe) the frequency will be higher 2) there is no doppler shift (the effect is the same as anobserver moving towards the source     and the source moving away from theobserver) 3) Both (II) and (III) are correct 4) P = 2 (L / g)     for asimple pendulum      There is a simple pendulum of somelength with the same frequency as the compound pendulum    and the frequency of a simple pendulum dependsonly on g & L.    Also, I1 = m L2 / 3 + ML2   is the moment of inertia of thependulum             I2 = 2 m L2 / 3 + 2 ML2   = 2I1       doublingthe masses    Since the torque will also double the frequencyremains the same

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