Answer: 0.4m
Explanation:
Given that:
Amplitude of wave = 2.0 m
Wavelength (λ)= ?
Frequency F = 500Hz
Speed V = 200 m/s
The wavelength is measured in metres, and represented by the symbol λ.
So, apply the formula:
Wavespeed V= Frequency F xwavelength λ
200m/s = 500Hz x λ
λ = 200m/s / 500Hz
λ = 0.4m
Thus, the wavelength is 0.4 metres
The refractive index for glycerine is

, while for air it is

.
When the light travels from a medium with greater refractive index to a medium with lower refractive index, there is a critical angle over which there is no refraction, but all the light is reflected. This critical angle is given by:

where n1 and n2 are the refractive indices of the two mediums. If we susbtitute the refractive index of glycerine and air in the formula, we find the critical angle for this case:
They traveling at -0.37/ms^
The north vectors add up as so the south vectors. Then subtract the two. For north its 4 + 5 = 9. South is 2 + 5 = 7. Then 9-7 = 2km North (D)