Answer:
T = 1.24 N
Step-by-step explanation:
The wave velocity is given by
v = √T /μ
Wave speed is also
v = λ f
Let's look for the wavelength that you rinse from an oscillation
λ = 3.5 / 4 = 0.875 m
The frequency is the time of an oscillation
f = 4 / t
f = 4 / 0.75 = 5.33 s⁻¹
We equal the equation is
λ f = √T /μ
T = λ² f² μ
Linear density is
μ = m / L
μ = 0.2 / 3.5
μ = 0.0571 kg / m
Let's calculate
T = 0.875² 5.33² 0.0571
T = 1.24 N