Answer:
wavelength = 0.968 m
frequency = 39.02 Hz
Explanation:
given data
mass = 0.0127 kg
force = 9.33 N
length = 1.93 m
to find out
wavelength and Frequency
solution
we know here linear density that is
linear density =
.........1
linear density =
linear density = 6.5803 ×
kg/m
so
wavelength will be here
wavelength =
..............2
here n = 4 for forth harmonic
wavelength = 
wavelength = 0.968 m
and
frequency will be for 4th normal mode of vibration is
frequency =
..........3
frequency = 
frequency = 1.036269 × 37.654594
frequency = 39.02 Hz
If we assume that the acceleration is constant, we can use on the kinematic equations:
Vf = Vi + a*t = 15 + 3*4 = 27 m/s
The answer to your question is AB is 50 kilometers.
50 kilometers