Besides different in density, are they different in any other ways, such as color, conductivity, magnetic property?
Do you have to involve arduino in this project to show some competence or are you finding solution to a problem you encounter and think arduino could help?
If I calculated correctly, the nylon ball has a density of 1.1g/cm^3 and the other is bit higher. You can just dump them in salt water (density between 1.0 and 1.2 depending on salt content), the nylon balls will float and the other balls all sink to the bottom.
To quote my project brief "The balls are identical in appearance and surface texture".
I chose to use the Arduino because I couldn't really see any feasible way to sort the two out with a calculated mass difference of 1.2g so I opted to do it eletronically.
Nylon66 ball has a density of 1.1g/cm^3 (I worked out mass to be 4.6g)
Acetal ball has a density of 1.4g/cm^3 (I worked out mass to be 5.8g)
You need to increase the gain from your amplifier, so you need a bigger resistor. Try that 2K2 one you have it won't do any harm if it is too high.
Check this video out
In it I tested using a 5v excitation and cycled through gain resistors of 10, 560, 1k pot, 2.2k with masses of 3g and 10g. Then the same using a 2v excitation.
Hi,
Can I clarify from what you're saying, with the 10g reference shown in your images, AnalogRead() shows 0, and at 0.5kg it shows 140 with a 5V excitation voltage on the load cell? Also, how are you measuring the 2V excitation voltage the scales use internally?
Cheers ! Geoff
Please check the video above within this post for my readings.
As for the 2V. I was curious to see what the digital scale used to excite the load cell. So I opened it up again, turned it on and measured the voltage across E+ and E- using a multimeter and got 2v (2.03). The scale is powered by two AAA batteries.
See if one ball rolls down a ramp faster than the other. That's how old slug detectors work.
http://physics-animations.com/Physics/English/angl_txt.htm If two cylindrical bodies are rolling down on a inclined plane then body which has the smaller inertia moment will reach the end of the plane first.
The balls will have different trajectories after leaving the end of the ramp. You can literally put two buckets down and catch each type of ball in a different bucket.
Another way to tell that would take less space would be to use momentum transfer. The same momentum applied to each should make them move at different speeds. Put in a jump ramp with a block so the faster one goes over while the slower is blocked.
I considered something similar but without the balls to test with I struck the idea off since I wasn't sure if the 1.2g difference would create enough of a trajectory difference.
The block could work but same problem although I suppose if there's any significant differnce in the eleasicity between acetal and nylon it might have a better chance.
I might have to find a physicist to help me work this out if the Arduino plan fails.
Now I am thinking about a simple balance. You put 5g weight on one side and introduce a ball to the other side. Gravity will tell you what to do.
A mechanical idea I like. Now I'm just a bit unsure of how to place the ball onto that balance without it dropping off.
Thanks for your responses guys I really appreciate it.
Here's the code I have uploaded to the Arduino:
void setup()
{
analogReference(INTERNAL);
// initialize serial communication with computer:
Serial.begin(9600);
}
void loop() {
const int sampleSize = 60;
float AnalogValueTotal = 0;
float AnalogValueAverange = 0;
for (int i=0; i < sampleSize; i++){
AnalogValueTotal = AnalogValueTotal + analogRead(A0);
}
delay(5);
AnalogValueAverange = (AnalogValueTotal)/sampleSize;
Serial.println(AnalogValueAverange);
}
