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EEJ MAIN Physics QUESTION #7031
Question 1
A travelling wave on a string with linear mass density $5\text{ g/m}$ is described by $y = 0.03 \sin(450t - 9x)$ in SI units. What is the tension maintained in the string?
  • $10\text{ N}$
  • $7.5\text{ N}$
  • $12.5\text{ N}$✔️
  • $5\text{ N}$
Correct Answer Explanation
Wave speed $v = \frac{\omega}{k} = \frac{450}{9} = 50\text{ m/s}$. The formula for wave speed in a string is $v = \sqrt{\frac{T}{\mu}}$. Squaring both sides gives $T = v^2 \mu$. Substituting the values: $T = 50^2 \times 0.005 = 2500 \times 0.005 = 12.5\text{ N}$.