background image

 

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rotate it about all three axes. The graph below shows the result. The graph has all 
three components of acceleration and the net acceleration (the square root of the sum 
of the squares of the accelerations). The bottom graph is the net acceleration. Notice 
that it stays near 9.8 m/s

2

 throughout all of this rotation.  

Rotating the 3-Axis Accelerometer 

The 3-Axis Accelerometer is designed to measure small accelerations with minimal 
electronic noise. The noise is typically on the order of 0.5 m/s

2

 peak to peak. The 

offset voltage (voltage output at 0 m/s

2

) will drift somewhat with temperature.  

Vernier produces three other accelerometers: 

 

25-

g

 Accelerometer (ACC-BTA). Use for collision experiments or for 

centripetal acceleration experiments with larger accelerations. 

 

Low-

g

 Accelerometer (LGA-BTA). This is a, one-dimensional version of the 

3-Axis Accelerometer. 

 

Wireless Dynamics System Sensor (WDSS). A 3-axis accelerometer, altimeter, 
and force sensor in one unit that communicates wirelessly with your computer. 

This sensor is equipped with circuitry that supports auto-ID. When used with 
LabQuest, LabQuest Mini, LabPro, Go! Link, SensorDAQ, EasyLink, or CBL 2, the 
data-collection software identifies the sensor and uses pre-defined parameters to 
configure an experiment appropriate to the recognized sensor. 

Do I Need to Calibrate the 3-Axis Accelerometer? 

You should not need to calibrate this sensor.  Each sensor is calibrated prior to being 
shipped to you. The measurement being made by this sensor is complex and can be 
difficult to analyze, so be sure to read the Frequently Asked Questions below. In most 
experiments you can simply use the default calibration, but then use the software’s 
zeroing option and zero the sensor along the axes.  
Most accelerometers, including this one, sense gravity as well as acceleration. This can 
make results more difficult to understand, but it provides an easy calibration method. 
Calibration may be done using the acceleration due to gravity. To calibrate the sensor 
for measuring acceleration in the horizontal direction, position the Accelerometer with 

 

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the arrows pointing down for the first calibration point. Define this as –9.8 m/s

2

 or  

–1 g. Rotate the Accelerometer so the arrows point up and use the reading for the 
second calibration point. Define this as +9.8 m/s

2

 or +1 g. The Accelerometer will then 

read 0 with no acceleration when held horizontally. Repeat this procedure for each 
axis. If you want to calibrate for measuring acceleration in the vertical direction, follow 
the procedure above, but define the first calibration point as 0 

g

 or 0 m/s

2

 and the 

second point as 2 

g

 or 19.6 m/s

2

.  

Using the 3-Axis Accelerometer as a Single Axis Accelerometer 

Since the 3-Axis Accelerometer is equivalent to three Low-g Accelerometers, you 
can use just one channel of it to study acceleration along a single axis. Just mount 
the accelerometer so that a particular axis is in the direction of interest and monitor 
just that channel. If the motion is linear, it will keep the analysis simple.  

Suggested Experiments 

Since the 3-Axis Accelerometer is equivalent to three Low-g Accelerometers, you 
can also do any experiment that uses only one or two axes. Examples include: 

 

Measure the acceleration of dynamics carts as they roll down inclines or have 
force applied to them. 

 

Measure acceleration 

vs

. time on elevators, remote-controlled cars, bicycles, or 

automobiles. 

 

Use the accelerometer to measure the tilt of an object. Since each channel of 
the accelerometer senses the vertical component of gravity, its reading will 
change as its orientation is changed from horizontal to vertical. You can 
measure angles to the nearest degree. 

The 3-Axis Accelerometer can also be used to collect data in more complex 
experimental settings such as: 

 

Amusement park rides such as roller coasters, swings, swinging ships, and Tilt-
a-Whirl. 

 

Bungee jumps done by dolls or humans. 

 

Place the accelerometer and interface in a padded box and toss it in the air. 
Compare the three individual accelerations to the net acceleration.  

3-Axis Accelerometer tossed in the air but not rotated 

In the graph above, the box was tossed in the air but not rotated. Notice that the x-
and z-axis accelerations before the toss are zero whereas the y-axis acceleration is 

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