Answer:
80m
Explanation:
u=20,R=?,sin theta=1,g=10
R=u²sin2theta/g
R=20²x2/10
R=400x2=800/10
R=80m
The frequency of a wave becomes higher due to the object moving at a fast pace coming towards you with shorter wavelengths (depending on the speed) aka the Doppler Effect.
Hope this helps
