Instead of changing the the frequency you can change the tension to produce the next higher harmonic. What percentage of the tension would produce the next higher harmonic?

Explanation:

This is a string resonance exercise, the wavelengths in a string held at the ends is

          λ = 2L₀ / n

where n is an integer

the speed of the wave is

           v = λ f

            f = v /λ

the speed of the wave is given by the characteristics of the medium (string)

           v =

we substitute  

            f =

to obtain the following harmonic we change n → n + 1

            f’ =  

In this case, it tells us to change the tension to obtain the same frequency.

            f ’= \frac{n}{2L_o} \  \sqrt{\frac{T}{\mu } }

how the two frequencies are equal

           (n + 1) = n

this is the relationship of the voltages to obtain the following harmonic,

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day