A mass of 0.40 kg, attached to a spring with a spring constant of 80 N/m, is set

Question

A mass of 0.40 kg, attached to a spring with a spring constant of 80 N/m, is set into simple harmonic motion. What is the magnitude of the acceleration of the mass when at its maximum displacement of 0.10 m from the equilibrium position? a. zero b. 5m/s^2 c. 20m/s^2 d. 10 m/s^2 The intensity level of sound 20 m from a jet airliner is 120 dB. At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound.) a. 90m b. 200m c. 150m d.120m If the frequency of a traveling wave train is increased by a factor of three in a medium where the speed is constant, which of the following is the result? a. amplitude is tripled b. wavelength is one third as big c. amplitude is one third as big d. wavelength is tripled A uniform bridge span weighs 50.0 a. 29.5 b. 32.5 c. 35.5 d. 65.0

Explanation / Answer

acceleration a = w^2*A

w = angular frequency = sqrt(k/m)

A = amplitude = 0.1 m

a = (k/m)*A = (80/0.4)*0.1 = 20 m/s^2 <<<----------answer

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Q6)

I0 = threshold intensity = 10^-12 W/m^2

intensity level = 10*log(I1/I0)

120 = 10*log(I1/I0)

120 = 10*log(I1/10^-12)

I1 = 1 w/m^2

for intensity level 100 dB

100 = 10*log(I2/I0)

100 = 10*log(I2/10^-12)

I2 = 0.01 w/m^2

I1/I2 = r2^2/r1^2

1/0.01 = r2^2/20^2

r2 = 200 m

option (b) <<<--------answer

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Q7)

v = lambda*f

speed remains constant in a given medium

lambda = v/f

as frequency increases lambda decreases to one third

option(b)

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