This is a concrete example of the Doppler effect. This effect is the change of frequency experienced by the listener or the observer with respect to their relative distance to the source of the sound. There can be two equations to be applied: to the approaching source, and to the receding source.
Approaching source:
frequency observed = [v/(v-v,source)]*frequency of source, where v is the velocity of sound . Substituting,
1000 = [340/(340-v,source)]*frequency of source <---- equation 1
Receding source:
frequency observed = [v/(v+v,source)]*frequency of source, where v is the velocity of sound . Substituting,
800 = [340/(340+v,source)]*frequency of source <---- equation 2
Rearranging equation 1: [1000(340-v,source)]/340 = frequency of source
Equation 2: 800 = [340/(340+v,source)]*frequency of source
Substituting equation 1 to equation 2:
800 = [340/(340+v,source)]*[1000(340-v,source)]/340
Solving using the scientific calculator under shift-solve feature,
v,source = 37.78 m/s
Therefore, the train is moving at 37.78 m/s.
Solar energy and Hydro is the correct option.
<h3>Which sources provide energy nowadays?</h3>
Today's energy supply is provided by solar energy and Hydro as compared to our ancestors because our ancestors have no modern technology to obtain energy from sun and water. They get energy from burning of fossil fuels and biomass.
So we can conclude that solar energy and Hydro is the correct option.
Learn more about energy here: brainly.com/question/13881533
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Well to prove a hypothesis false, you are gonna have to conduct the experiment to see the final answer/ product. If it is what your hypothesis said you are correct, if it is the opposite or different from your hypothesis it is false/wrong.<span />
Answer:
A The shorter the wavelength the higher the frequency the longer the lower, hope this helps, thanks.