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In a loudspeaker, an electromagnetic coil rapidly drives a paper cone back and forth, sending out sound waves.Part AIf the cone of a loudspeaker moves sinusoidally at 1.8 kHz with an amplitude of 4.5 μm, what is the cone's maximum speed?Part BWhat is the cone's maximum acceleration?

User Katrasnikj
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Part A

The vibration of the speaker causes simple harmonic motion. The formula for calculating the maximum speed, vmax is expressed as

vmax = wA

where

w = angular speed

A = amplitude

Recall,

w = 2 x pi x f

where

f = frequency

pi is a constant whose value is 3.14

From the information given,

f = 1.8 KHz

we would convert from KHz to Hz

Recall,

1 KHz = 1 x 10^3 Hz

1.8 KHz = 1.8 x 10^3 Hz

By substituting the values into the formula, we have

w = 2 x 3.14 x 1.8 x 10^3

Also,

A = 4.5 μm

We would convert from μm to m

Recall,

1 μm = 1 x 10^-6 m

Thus,

4.5μm = 4.5 x 10^-6m

By substituting w = 2 x 3.14 x 1.8 x 10^3 and A = 4.5 x 10^-6 into vmax = wA, we have

vmax = 2 x 3.14 x 1.8 x 10^3 x 4.5 x 10^-6

vmax = 0.051 m/s

Part B

The formula for calculating max acceleration, Amax is

Amax = w^2A

By substituting w = 2 x 3.14 x 1.8 x 10^3 and A = 4.5 x 10^-6 into the formula, we have

Amax = (2 x 3.14 x 1.8 x 10^3)^2 x 4.5 x 10^-6

Amax = 575 m/s^2

User Epx
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