Question

4.2 characteristics of light
a 30.0 cm sound wave travels through a magnesium bar with a frequency of 15.3 khz. what is the speed of sound in magnesium?
○ 918 m/s
○ 5.10×10⁴ m/s
○ 4590 m/s
○ 1.96×10⁻⁵ m/s

Explanation:

Step1: Convert units

Convert the wavelength $\lambda = 30.0\ cm$ to meters. Since $1\ m=100\ cm$, then $\lambda=0.300\ m$. Convert the frequency $f = 15.3\ kHz$ to Hz. Since $1\ kHz = 1000\ Hz$, then $f = 15300\ Hz$.

Step2: Use the wave - speed formula

The formula for the speed of a wave is $v=\lambda f$. Substitute $\lambda = 0.300\ m$ and $f = 15300\ Hz$ into the formula. So $v=(0.300\ m)\times(15300\ Hz)=4590\ m/s$.

Answer:

C. 4590 m/s