Explanation:
acceleration = change in velocity / change in time
a = v2-v1
- - - - - -
t
V1 = 0 ( since she stopped)
V2 = 9 m/s
t =15s
a = 9 - 0
- - - -
15
= 0.6m/s^2
Answer:
<u>because of the doppler effect</u>
Explanation:
<em>Remember</em>, the doppler effect refers to the changes in sound (frequency of sound) observed by a person who is in a position relative to the wave source.
In this example, we notice as the train comes closer to the boy, the sound becomes louder also increasing the pitch slightly, the doppler effect sets in when the train passes the boy because the boy notices a decrease in the pitch of the moving train.
We learn from the change in the observed sound of the train that the frequency of the sound is determined by the distance of the observer from the wave source.
In other words, the closer the source of the sound to the observer; the faster it travels to the observer, however, the farther it is; the lesser it is; the greater the sound heard.
The ions are in fixed positions.
Explanation:
Ionic solids are poor conductors of electricity because their ions are fixed in position. Their ions are not free to move about. They are fixed in crystal lattices.
- For the conduction of electricity, compounds must possess free mobile electrons and moving ions in solution.
- Ionic compounds are formed by the electrostatic attraction between a metallic and non-metallic ion.
- They actually contain ions but their ions are locked up.
- They are not free to move about.
- Electrical conduction involves ion mobility.
- In molten and aqueous forms, they are able to conduct electricity because their ions are then mobile.
learn more:
Ionic compound brainly.com/question/6071838
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