Greeting the Sensors
Flipping out over accellerometers:
PASCO Model CI-6558 Rev A
Introduction:
The Acceleration Sensor is designed to measure accelerations ranging up to 5 times the
earth's gravitational eld with an accuracy of 0.01 g (g = acceleration of gravity, 9.8 m/s
It produces a bipolar output that may vary from +5 g to -5 g, depending on the direction of
acceleration. It is capable of resolving changes in acceleration on the order of 1 milli-g when a
gain of 10 is applied in Capstone
It has two built-in features for con guring it to a particular application:
(1) a tare button, used to set the output of the sensor to 0 regardless of the acceleration being
applied (allows the e ect of the earth's gravitational
eld to be nulled);
(2) a lter with two settings —"slow" or "fast", setting the frequency response of the
Acceleration Sensor to a range suitable for the application.
For experiments such as measuring the acceleration of elevators, roller coasters, and
automobiles, select the "slow" setting. The slow lter reduces errors due to high frequency
vibrations and noise. For applicationsinvolving mechanical systems, such as cart collision
experiments, select the fast setting.
The Data Studio software will display the output of the Acceleration Sensor in units of m/s
2
, or
in terms of g.
Very small values of acceleration can be measured by taring the sensor and adding gain in
Data Studio.
Verify the Acceleration Sensor's Performance in the Earth's Gravitational Field:
8. Connect the Acceleration Sensor to the computer interface with the interface cable
(see Figure 1a) and set up Capstone. Open a Digital Display and select Acceleration (g)
from the pop-up menu. Set the lter switch on the sensor to SLOW.
9. Place the sensor
f
at on a level surface with the arrow indicating direction of sensitivity
parallel to the ground (Figure 3a) and press the tare button.
10. Orient the sensor so the arrow on the label is perpendicular to the ground (see Figure
3b). Monitor Data in Capstone.
11. Observe that Capstone is displaying a value for acceleration of either plus or minus 1g.
12. Rotate the sensor 180° around its major axis so the arrows point in the opposite
direction.
13. Observe that Data Studio now displays 1 g with the opposite sign as observed before.
14. Can you imagine a way to measure the tilt angle of the sensor? (Hint: tilt angle =
arcsin(acceleration in g) ).
Figure 5. Response o
f
the Acceleration Sensor to the earth's gravitational feld
