Answer:
By nature, laws of Physics are stated facts which have been deduced and derived based on empirical observations. Simply put, the world around us works in a certain way, and physical laws are a way of classifying that “working.”
Answer:
m = 0.0125 kg
Explanation:
Let us apply the formula for the speed of a wave on a string that is under tension:

where F = tension force
μ = mass per unit length
Mass per unit length is given as:
μ = m / l
where m = mass of the string
l = length of the string
This implies that:

Let us make mass, m, the subject of the formula:

From the question:
F = 20 N
l = 4.50 m
v = 85 m/s
Therefore:

V = f * wavelength
as we know electromagnetic wave has speed equal to light, so
3 * 10^8 = f * 1.3
f = 2.3 * 10^8 hertz
f = 230 mega hertz