Marble Speed Trap

Recently, Dan gave E11 the assignment to figure out how to use the light sensors with the nxt kit to measure the velocity of a marble going down the track. If you’ve been a reader for a while, then you might remember we took this on without the sensors earlier this year. E11 rose to the challenge, with some “encouragement” here and there and here are the results.

The trap- E11 designed it so that the sensors could measure the speed of the marble going through

close up of the read out- recorded in inches per second and miles per hour. Cool.

here they are showing a read out- the highest velocity recorded was 9 miles per hour

Basically, the first light sensor will sense when the marble has gone by it which starts a timer. The second sensor will know when the marble goes by it too stopping the timer and reading its value (as summarized by E11 himself).

Stay tuned for more NXT challenges. Our new FLL (First LEGO League) season is underway and the team has met once and will meet again on Friday.

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  1. says

    Very cool. Good job in figuring out how to make it work.We haven't done enough with our NXT. We have done a couple of silly things like a sled dog team in honor of the Iditarod and a reindeer and sleigh, but I'd like it if the kids started solving more problems.I think both of the projects my boys did came from this website, which has lots of cool projects: really enjoy your blog!Thanks,Sarah

  2. says

    Thanks Sarah. I will check out the website.We also have some books we've used to do projects. We found them on Amazon.He's supposed to be working on a speed trap using ultrasonic sensors right now. I have not checked on progress yet.Thanks for reading!Heather

  3. Jim Baratono says

    We are working on a science project where we need to measure speed down a ramp just like this one in the marble example – we are attempting to use the NXT to do the same thing, but we can’t figure out the programming and we are in a real jam – I was hoping to get the NXT code that you used in the marble speed example – I would super appreciate it if you could send it to me via e-mail! Thanks!

    • Heather Woodie says

      Jim, This was quite a while ago, but I’ll check in with my son to see if he remembers his basic code. Stay tuned!


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