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Oscillations

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Question : 9 of 25
Marks: +1, -0
A spring having a spring constant 1200 N m−1^{-1} is mounted on a horizontal table as shown in figure. A mass of 3 kg is attached to the free end of the spring. The mass is then pulled sideways to a distance of 2.0 cm and released.
Determine (i) the frequency of oscillations of the mass, (ii) maximum acceleration of the mass, and (iii) the maximum speed of the mass.
Solution:  
Here, m = 3.0 kg ; k = 1200 N m−1^{-1}, A = 2 cm = 0.02 m
(i) The frequency of oscillations of the attached mass is
υ=12πkm\upsilon = \frac{1}{2\pi} \sqrt{\frac{k}{m}} =12×3.1412003=3.2 s−1= \frac{1}{2 \times 3.14} \sqrt{\frac{1200}{3}} = 3.2\,\text{s}^{-1}
(ii) The maximum acceleration of the mass is
∣amax∣=ω2A=kAm(∵ω=km)|a_{\text{max}}| = \omega^{2} A = \frac{k A}{m} \left(\because \omega = \sqrt{\frac{k}{m}}\right)
=1200×0.023=8 m s−2= \frac{1200 \times 0.02}{3} = 8\,\mathrm{m}\,\mathrm{s}^{-2}
(iii) The maximum speed of the mass is
vmax=Aω=Akmv_{\text{max}} = A \omega = A \sqrt{\frac{k}{m}} =0.02×12003=0.4 m s−1= 0.02 \times \sqrt{\frac{1200}{3}} = 0.4\,\mathrm{m}\,\mathrm{s}^{-1}
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