PT Graph Prelab Quiz

Question 1

how does a motion detector work?

Answer 1

emits short bursts of ultrasonic sound waves & then receives the echo of the waves returning to it

Question 2

what does the LabQuest measure?

Answer 2

the time it took the wave to go out and come back

Question 3

how does the LabQuest use its data?

Answer 3

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

Question 4

How does distance affect the echoes?

Answer 4

weaker they farther they go

Question 5

how does the sensitivity of echo detection change in proportion to distance?

Answer 5

more sensitive the farther it goes

Question 6

ultrasound

Answer 6

cyclic sound pressure wave w/ frequency (waves/sec) greater than the upper limit of human hearing

Question 7

what frequencies do ultrasound devices use?

Answer 7

20kHz –> several gigahertz

Question 8

what is ultrasonic imaging used for?

Answer 8

human and veterinary medicines

Question 9

what is ultrasound used for?

Answer 9

to detect invisible faults, clean, mix, and accelerate chemical processes

Question 10

which tab is the “meter” screen

Answer 10

1st tab

Question 11

which tab is the “graph” screen

Answer 11

2nd tab

Question 12

where do u find the option “data collections”?

Answer 12

in the “Sensors” tab of the “meter” screen

Question 13

what should the rate and length of the samples be and where do u change them?

Answer 13

2 samples/per sec, 8 seconds, data collection

Question 14

how do u change to the “manual” option?

Answer 14

graph –> graph options –> top right

Question 15

what should the y and x axis be?

Answer 15

top: 7m
bottom: 0m

Question 16

how many degrees is the cone of sound?

Answer 16

30 degrees

Question 17

at what distance does the motion detector not work as well?

Answer 17

less than 0.5 meters

Question 18

what is the origin?

Answer 18

motion detector

Question 19

why does the setting have to be manual, not auto?

Answer 19

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

Question 20

Why does the sampling rate have to be 2, not 20?

Answer 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