Lab Quest Hand Held Data Collection
From time to time the Lab Quest devices will be available to use. We can only use them for data collection if we have the appropriate sensors to do the data collection.
They are touch screen (stylus, not fingertip) and they also include buttons on the front to navigate things.
There will be some opportunities to explore and jot down notes in this activity so that future use of these devices will be less confusing (hopefully…)
There are also ports on the side of the hand held device. The motion detector you will be using will need to go in the side port. It is important to NEVER FORCE ANYTHING. If you are having trouble, please ask.
Once a sensor is plugged in you will get a live reading of the sensor data (top pic with 0.022 N), once you choose to run you will begin to generate a “something vs. time” graph.
There are default values for how long the handheld will collect data and how often it will sample data during that time (ex: collect data for 5 seconds, collecting a data point every 0.05s. If you have done the spark timer activity already, this might sound a bit familiar).
As you conduct an investigation using the motion detector you could adjust the time of data collection and the sampling rate. I recommend only tinkering with the time of data collection
Collecting Data with Motion Detector
On the side of the motion detector is a port labeled “DIG/SONIC” one end of the provided cable goes here (it can only fit one way). The other end of the cable needs to go into a port on the side of the Lab Quest (DIG 1).
Once you tilt the motion sensor (like in the picture above) you will see a slider switch on the detector.
This is the sensitivity setting. Normal is for people or larger things or measurements that will need to be taken over larger distances. Track would be for physics carts or for smaller things or close things.
You will notice that the further away your moving object gets the more likely the background objects can mess with the read out.
There is a clamp for the motion detector that attached to the back of the device and can allow you to attach the motion detector to the lab table (this will help with data collection.
Let’s Get Started!
Activity 1: Constant (non-zero) velocity
· Mount clamp to lab table so that the line of sight for the detector is “clear”
· Have the setting on “track”
· Turn on the Lab Quest (silver button on upper left corner) (Page 1 Quick Data Collection Step 1)
· You should hear a clicking sound and there should be a green light on the front of the detector
· Move your hand back and forth in front of the sensor. You should see the numbers changing on the screen.
· When you get “too close” the value will not go to 0 (I got 0.174m and then the numbers went all jumpy)
Collecting data.
Before you collect your data, we are going to zero out the motion detector. That way we are establishing a coordinate system for where your object (hand, person, etc) starts out has a value of 0m.
Select “Sensors” from the menu. Make sure your object is at the “zero location” and select Zero (DIG 1). This make the display read 0.
Your goal is to produce a data set where your object is moving at a constant velocity (for the first few ticks of the clock the object will be getting up to speed, but we are going to focus on the constant velocity part).
To start collecting data press the play button or icon on the screen (Page 1 Quick Data Collection Step 3). There is a bit of a lag from the moment of “start” till the data actually begins collecting.
I believe the data collection time is set to 5s by default
Once the data is collected you will have the following two graphs: Position vs. Time and Velocity vs. Time.
If your object moved at a constant velocity, the position vs. time graph should be a line of positive slope. The velocity vs. time graph should be close to a horizontal line. If not, try collecting your data again.
Analyzing Data
Using the stylus you can click on points on the position vs. time graph and you will see the readout on the right change. It will update the position, velocity, and time that each of those values occurred.
You can see the menu at the top now has more options. For now we don’t really need them, but in future labs we might.
If you look at the top of the screen you will see an icon with an XY on a table (also featured in image above).
Click on this icon. You will now be presented with a data table of your data (by default a data point was collected each 0.05 seconds. So a graph of 5 seconds of motion contains 100 data points… good thing we didn’t collect by hand)
Sketch the position vs. time and velocity vs. time graphs below:
Once you are done with your data, choose Fileà New, and agree to discard the data
Activity 2: Acceleration
· Reposition your object and re-zero the motion detector
Your goal this time is to record accelerating motion.
Try to have a nice uniform acceleration from rest to some constant velocity. Try to get to speed before the 5 seconds runs out.
Follow the same data collecting steps as you did for Activity 1
When you look at your data your position vs. time graph should be a parabola (open upwards)
When you look at your velocity vs. time graph it should be a line with positive slope.
If you didn’t get these shapes, try again. Your object should be moving away from the sensor.
Sketch your position vs. time and velocity vs. time graphs below:
Once you are done with your data, choose Fileà New, and agree to discard the data
Activity 3: Other Motion
· Reposition your object about 1m away from the detector and re-zero.
Collect data for constant velocity motion towards the detector.
Sketch your graphs below
How did these graphs look compared to the graphs in activity 1?
· Reposition your object about 1m away from the detector and re-zero.
Repeat the experiment from Activity 2, but have the object moving towards the detector at a constant velocity when the timer starts. Then increase speed constantly.
Sketch your graphs below
How do these graphs look compared to the graphs in activity 2