Answer on Question #50089 – Physics - Mechanics | Kinematics | Dynamics
Vibrations
A horizontal frictionless mass-spring system is set to oscillate at 10 H z 10\,\mathrm{Hz} 10 Hz . If the spring constant is 450 N / m 450\,\mathrm{N/m} 450 N/m , what is the mass of the object?
Solution:
f = 10 H z − frequency ; k = 450 N m − spring constant ; m − mass of the object ; \begin{array}{l}
f = 10\,\mathrm{Hz} - \text{frequency}; \\
k = 450\,\frac{\mathrm{N}}{\mathrm{m}} - \text{spring constant}; \\
\mathrm{m} - \text{mass of the object};
\end{array} f = 10 Hz − frequency ; k = 450 m N − spring constant ; m − mass of the object ;
Formula for the frequency for the mass-spring system:
f = 1 T = 1 2 π m k f = \frac{1}{T} = \frac{1}{2\pi \sqrt{\frac{\mathrm{m}}{k}}} f = T 1 = 2 π k m 1 2 π f m k = 1 2\pi f \sqrt{\frac{\mathrm{m}}{k}} = 1 2 π f k m = 1 4 π 2 f 2 m = k 4\pi^2 f^2 \mathrm{m} = k 4 π 2 f 2 m = k m = k 4 π 2 f 2 = 450 N m 4 ⋅ 3.14 ⋅ ( 10 H z ) 2 = 0.36 k g \mathrm{m} = \frac{k}{4\pi^2 f^2} = \frac{450\,\frac{\mathrm{N}}{\mathrm{m}}}{4 \cdot 3.14 \cdot (10\,\mathrm{Hz})^2} = 0.36\,\mathrm{kg} m = 4 π 2 f 2 k = 4 ⋅ 3.14 ⋅ ( 10 Hz ) 2 450 m N = 0.36 kg
Answer: mass of the object is equal to 0.36 k g 0.36\,\mathrm{kg} 0.36 kg .
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