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
A I think it was sorry if not
If you don't ventilate your boat after fueling, the gas fumes will stay in the bottom of boat and this is very dangerous.
Explosion can happen if you don't ventilate your boat after fueling so to avoid any explosion or any problem, you have to follow the proper procedure for fueling the boat.
So always ventilate your boat after fueling.
Answer:2.23 m/s
Explanation:
Given
Mass of person and vehicle is 
Total work done is 
Friction consumes one-third of the energy
The remaining two-third is consumed to increase the kinetic energy
