A speaker fixed to a moving platform moves toward a wall, emitting a steady sound with a frequency of 215 hz. A person on the platform right next to the speaker detects the sound waves reflected off the wall and those emitted by the speaker.

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i havent taken the psat, but i have the sat, make sure to bring some snacks, because youre in there forever, 2 sharp number two pencils, an sat approved calculator, and maybe a jacket.   your phone and any books will be taken up, so don't try to bring them(but they will be given back at the end of the testing).   good luck!   i hope you do well!

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it's true that when your child reaches the age of eighteen, they are legally seen as an adult and are legally responsible for their own behavior instead of their parents. they can't break laws, of course – being 18 just means you can be tried as an adult, not that you're free to do anything you .

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