This is the dual range force sensor.
It is used in several of our manuals.
It shows up in the physics book, the middle school book, physical science, and the elementary manual.
It is used across a lot of different curriculum.
It is essentially a spring scale,
and the way it operates is if you apply a pull to it or a push to it,
it is measuring the force that you are applying to the sensor.
It is a dual-range force, so you have two different settings here.
There is +/- 10 Newtons and +/- 50 Newtons,
and the idea is that you can set this for what you think the forces you may have,
so you are adjusting the sensitivity on the scale by simply changing the switch from one to the other.
This hole here is to allow you to attach this to maybe a table clamp.
You want to mount this up high and attach a spring to it with a mass going up and down or weight something.
There is a nice lab from the math book where you put a cup in there and put pennies in,
so you are looking at what happens as you add pennies.
So that is how you might use this.
You can mount this to our cart and track system and, if you did that,
you could remove the hook that comes with it and attach the bumper.
So maybe you are doing a collision experiment and you wanted to collide with this
and measure what happens with the car as it collides with that.
That is what that is for.
Let me take that back off and put my hook back on.
Now, on the other end of the sensor here,
I can remove this screw and I can attach the handle that comes with it.
The idea here is that if I wanted to pull something with the sensor I can attach this handle and be able to pull it.
I am going to do this.
I have this block of wood and I am going to attach the sensor to it
so that when I pull the block of wood across the table top.
I want to measure the force that I am applying to the block.
I am going to try to pull this along with a constant velocity and measure the force as I do that.
The real advantage of using this device over using a spring scale to do the same thing
is that the spring scale is going to vary back and forth
and you will ask the students to read one of the values
and it is going back and forth there you might not be able to see that.
This will allow me to record it, so essentially it is a recording spring scale.
So we are ready to collect data and it is an analog sensor, so I am going to plug it into the LabQuest,
and when I do this it auto detects the sensor and we come up here with the meter screen.
It is giving me a current reading it is saying right now I have got .27 Newtons there.
What is happening is I am actually applying a little bit of force to this sensor.
If I push back just a hair so the string is not pulling on it, we see that that drops down.
One thing about this sensor is that you are going to want to zero it in the orientation that you plan to use the sensor.
What I mean by that is that the sensor is going to give me different values depending upon the orientation.
If I hang it this way then the weight down there is going to change it.
If I go this way it may change.
Zeroing the sensor allows it to read zero before I start doing this.
To do that, I am just going to go to the meter, and I tap on the meter and on the very top it says 'Zero',
so I press 'Zero', and I am getting close to a zero value.
What I want to do next is drag the block across the table top,
and I want to be collecting the data as I do this.
So I want to move the block over here a bit, and now I am ready to collect.
The default collection time is 10 seconds here, I think at 50 samples per second, and I am going to press 'Collect'.
Then slowly drag this across the table top.
If we take a look at our data now, we see that at first I am not pulling, and then I pull.
All of a sudden, the block starts to slide, and I am trying to pull this along with a constant velocity.
The surface is not all that smooth. There is a little bit of roughness which is grabbing and letting go.
That is what we are measuring here.
What I might be interested in doing is looking at the mean force applied to the block across this time period.
To do this, I am going to select the region of the graph where I am actually pulling the block,
go to 'Analyze', and I go down to 'Statistics', and now check the box next to there.
Over there on the left hand side, it is telling me what the minimum, maximum, and mean force applied to the block.
The mean force for that time period is 0.634 Newtons.
So this is just a simple experiment you could do.
Again, this is a useful sensor to use across the curriculum,
so it is definitely a good one to have.