Ah hah ! That description fits things like mass, linear momentum,
energy, angular momentum, electric charge, and politicians. They
never appear or disappear, they just move from place to place.
We say that those quantities are conserved.
Answer:

Explanation:
Given:
- original frequency of the wave,

- velocity of the blood stream moving away,

<u>Doppler shift is given as:</u>

where:
s = velocity of ultrasound in blood = 
velocity of sound source towards the observer
velocity of the observer away from the source


Therefore the shift in frequency:


The summary of the step you might use to carry out an investigation using scientific method include:
- Observation
- Hypothesis
- Experiment
- Conclusion
<h3>What is Scientific method?</h3>
This is defined as a systematic approach which helps to predict how several elements in the universe works.
This usually starts with observing a phenomenon and making a hypothesis. This is usually followed by conducting experiment to ascertain its authenticity before a conclusion is drawn.
Read more about Scientific method here brainly.com/question/17216882
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An element is neutral when the charged is equal to zero. This means that the number of electrons and protons are equal. When an object has a NEGATIVE charge, its electrons are more than its protons. Also, the object has a POSITIVE charge when the number of its electrons are fewer compared to the number of the protons.
Carbon is the answer to the problem