Measure. Analyze. Learn.
Hi, this is Dave Vernier, and I'm going to introduce you to
our new Projectile Launcher.
Basically, it's a system to launch steel ball bearings,
in a very reporducable way, using air pressure.
The system comes with some wax tape,
which you can lay down on the table,
and you'll get a mark everytime the ball hits it.
Today, just before this video shoot,
I shot onto this tape, about range about 1.5 meters.
and you see a got a cluster of five hits pretty close together.
Let's take a look at how the thing works.
Basically, you've got a control here,
which is a limit valve on the pressure.
So, you pump up pressure, but the pressure will, at some point,
start bleeding off, so that you get a set pressure,
controlled by that knob.
You can control the launch angle right here.
And, the neat thing about this design,
is that no matter how you change the angle,
the launch point is always right there.
14.6 centimeters above the table.
It doesn't move horizontally or vertically as I rotate this,
which makes some experiments easier.
The system does require power.
You can either get power from a LabQuest power supply,
which you connect right there.
Or, the better option is to connect the Projectile Launcher
to one of our interfaces.
Here I'm using a LabQuest 2,
you could use an origianl LabQuest,
you could use a LabQuest Mini, or you could use a LabPro.
That both supplies the power needed,
but more importantly, it connects you to the two built-in
photogates, which are right here and here.
They're five centimeters apart, and they're
right at the point where the ball comes out.
So, with these photogates, you can measure the speed
of the ball very acuratly right at launch time.
And, that opens the door to all kinds of interesting experiments,
For example, you can have the students launch the ball
into their hand, measure the speed,
and then, they have to calculate where the ball will hit,
and put the target at the spot.
Here, we have a little cup, we're going to try to hit later.
If you want to make that math easier,
you can raise the cup up, the target up,
so that it's the same height as our launcher.
And then, that makes that calculation very simple.
If you want to make it tougher, then you don't do that,
and then the students have to allow for the height change.
That's a better calculation for advanced students.
So, let's try a launch.
First, I'm going to put on my safety glasses. Two pair included.
Now, I'm going to pump up the pressure.
And, as I pump, I pump until I hear the chirping sound,
which means the pressure is bleeding off, we're at the limit.
Now, I want to start data collection on my interface,
because I do want to get the speed.
And, one more safety feature is, to launch the ball,
I have to both hold the arm button,
and the fire button at the same time.
And, let's give it a shot.
[Whosh of air] - [Clunk of ball into cup]
We hit the target, and you might have seen some
lentle beans fly out of it.
We put those in to absorb the impact, so it doesn't bounce out.
We should look here, we did measure the time.
We got 4.047 meters per second for the launch speed.
We think your student will have a lot of fun with this system.
Please refer to out web site if you have questions.