Question

A university physics professor buys 100 of string and determines its total mass to be 0.150 . This string is used to set up a standing wave laboratory demonstration between two posts 3.0 apart.If the desired second harmonic frequency is 35 , what should be the required string tension?

Answer 1

A university physics professor buys 100 m of string and determines its total mass to be 0.150 kg. This string is used to set up a standing wave laboratory demonstration between two posts 3.0 m apart. If the desired second harmonic frequency is 35 Hz, what should be the required string tension?

**Solution:**

Fundamental frequency is $\left(\frac{35}{2}\right) Hz$.

$f = \left[\frac{1}{2L}\right] \cdot \sqrt{\left(\frac{T}{m}\right)}$ where m is mass per unit length

$$m = \frac{0.15}{100} = 0.0015 \frac{kg}{m}$$ $$\left(\frac{35}{2}\right) = \left[\frac{1}{2 \cdot 3}\right] \sqrt{\left(\frac{T}{0.0015}\right)}$$

Solving

$$T = 16.54 \, N$$

Answer: $T = 16.54 \, N$.