PT Graph Prelab Quiz Flashcards
how does a motion detector work?
emits short bursts of ultrasonic sound waves & then receives the echo of the waves returning to it
what does the LabQuest measure?
the time it took the wave to go out and come back
how does the LabQuest use its data?
uses the time it took the wave to go out and back and the speed of sound in air to determine the distance to the nearest object
How does distance affect the echoes?
weaker they farther they go
how does the sensitivity of echo detection change in proportion to distance?
more sensitive the farther it goes
ultrasound
cyclic sound pressure wave w/ frequency (waves/sec) greater than the upper limit of human hearing
what frequencies do ultrasound devices use?
20kHz –> several gigahertz
what is ultrasonic imaging used for?
human and veterinary medicines
what is ultrasound used for?
to detect invisible faults, clean, mix, and accelerate chemical processes
which tab is the “meter” screen
1st tab
which tab is the “graph” screen
2nd tab
where do u find the option “data collections”?
in the “Sensors” tab of the “meter” screen
what should the rate and length of the samples be and where do u change them?
2 samples/per sec, 8 seconds, data collection
how do u change to the “manual” option?
graph –> graph options –> top right
what should the y and x axis be?
top: 7m
bottom: 0m
how many degrees is the cone of sound?
30 degrees
at what distance does the motion detector not work as well?
less than 0.5 meters
what is the origin?
motion detector
why does the setting have to be manual, not auto?
If it was set to auto, it would amplify the appearance of even the smallest fluctuation in position readings, creating a graph that superficially makes it look like a still object was jumping all over the place
Why does the sampling rate have to be 2, not 20?
If the sampling rate was too high, the motion detector would pick up excessive amounts of noise in the signals it received, making it impossible to create a smooth line on a PT graph
