1. a. longitudinal waves.
There are two types of waves:
- Transverse waves: in transverse waves, the oscillations of the wave occur in a direction perpendicular to the direction of propagation of the wave
- Longitudinal waves: in longitudinal waves, the oscillations of the waves occur parallel to the direction in which the waves are travelling.
So, these types of waves are called longitudinal waves.
2. d. a medium
There are two types of waves:
- Electromagnetic waves: these waves are produced by the oscillations of electric and magnetic field, and they can travel both in a medium and also in a vacuum (they do not need a medium to propagate)
- Mechanical waves: these waves are produced by the oscillations of the particles in a medium, so they need a medium to propagate - therefore, the correct choice is d. a medium
3. a. AM/FM radio
Analogue signals consist of continuous signals, which vary in a continuous range of values. On the contrary, digital signals consist of discrete signals, which can assume only some discrete values. For AM and FM radios, signals are transmitted by using analogue signals.
Answer:
A
Explanation:
Becuse its complete number
The astronaut would go the opposite direction due to Newton’s third law of -10N, -10N, -9N, -9N
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Edwin Hubble calculated the expansion rate of the
universe. The evidence that he base his calculation is the differences in
redshift for galaxies. The answer is letter B. the red shift of galaxies was
directly proportional to the distance of the galaxy from earth. It means that bodies farther away from Earth
were moving away faster. The Hubble’s constant is the ratio of distance to
redshift equal to 170 kilometers per second per light year of distance.
