Answer:A compound is a substance formed when two or more elements are chemically joined.
Explation:Water, salt, and sugar are examples of compounds.
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Answer: 0.4 m
Explanation:
Given
Speed of ambulance, vs = 61.9 m/s
Speed of car = 28.5 m/s
Frequency of ambulance siren, f = 694 Hz
Velocity of sound in air, v = 343 m/s
With speed of ambulance being (61.9 m/s) -> We solve using
fd = f(v + vr) / (v - vs), where vr = 0
fd = 694 * (343 + 0) / (343 - 61.9)
fd = 694 * (343 / 281.1)
fd = 694 * 1.22
fd = 847 Hz
Recall,
λ = v/f
λ = 343/847
λ = 0.4 m
Therefore, the wavelength of the sound of the ambulance’s siren if you are standing at the position of the car is 0.4 m
<span>C is the correct answer. Electron microscopes require a vacuum to work, so living cells cannot be seen because they cannot respire. Light microscopes use a ray of visible light instead of a beam of electrons to magnify something so it can be seen by the naked eye. There are two different types of electron microscope: transmission (TEM) and scanning (SEM).</span>
