The answer OC. It can be changed only if all scientists approve the change
Ans: Beat Frequency = 1.97HzExplanation:
The fundamental frequency on a vibrating string is

<span> -- (A)</span>
<span>here, T=Tension in the string=56.7N,
L=Length of the string=0.66m,
m= mass = 8.3x10^-4kg/m * 0.66m = 5.48x10^-4kg </span>
Plug in the values in Equation (A)
<span>so </span>

<span> = 197.97Hz </span>
<span>the beat frequency is the difference between these two frequencies, therefore:
Beat frequency = 197.97 - 196.0 = 1.97Hz
-i</span>
7.5 x 10⁻¹¹m. An electromagnetic wave of frecuency 4.0 x 10¹⁸Hz has a wavelength of 7.5 x 10⁻¹¹m.
Wavelength is the distance traveled by a periodic disturbance that propagates through a medium in a certain time interval. The wavelength, also known as the space period, is the inverse of the frequency. The wavelength is usually represented by the Greek letter λ.
λ = v/f. Where v is the speed of propagation of the wave, and "f" is the frequency.
An electromagnetic wave has a frecuency of 4.0 x 10 ¹⁸Hz and the speed of light is 3.0 x 10⁸ m/s. So:
λ = (3.0 x 10⁸ m/s)/(4.0 x 10¹⁸ Hz)
λ = 7.5 x 10⁻¹¹m
Speed= Distance/Time
Distance=24m
Time= 5seconds
Speed= 24/5= 4.8m/s