Answer :
This question involves the concepts of the law of conservation of energy and kinetic energy.
The girl's fastest speed is "3.7 m/s".
According to the law of conservation of energy, the girl will have the fastest speed at mean position, which will be calculated as follows:
Loss in Potential Energy = Gain in Kinetic Energy
[tex]mg\Delta h=\frac{1}{2}mv^2\\\\v=\sqrt{2g\Delta h}[/tex]
where,
v = maximum speed = ?
g = acceleration due to gravity = 9.81 m/s²
Δh = change in height = 1.3 m - 0.6 m = 0.7 m
Therefore,
[tex]v=\sqrt{2(9.81\ m/s^2)(0.7\ m)}[/tex]
v = 3.7 m/s
Learn more about the Law of Conservation of Energy here:
https://brainly.com/question/381281?referrer=searchResults
