We don't typically post items related to science fairs (I get a lot of them - they're always enjoyable but most aren't related to NXT but just use an NXT robot to facilitate something else), but I thought this was an interesting project worth sharing, especially because it's using an NXT to obtain the results - I've posted Keizo's results in the accompanying image.
BTW - Keizo is in 4th grade.
Thanks for sending this in Keizo! - Jim
How Much Electricity Is Used When A Robot Pulls A Certain Weight
By Keizo M.
Hypothesis: I think that the robot will use twice as much electricity when the weight of the car is doubled.
Why I Chose This Project: Last year I got a LEGO Mindstorms NXT 2.0 for my birthday. I really enjoyed it, but while using it, I noticed that the batteries run out quickly. I decided to measure how much electricity would be used when a robot pulls a weight.
Materials: -Lego Mindstorms ® NXT 2.0 -Digital Voltmeter -6 Rechargeable Batteries -Weights
1) Make a robotic car out of Lego Mindstorms NXT 2.0
2) Program the car to go forward and backward for 10 minutes
3) Charge the batteries
4) Measure volts in batteries
5) Put batteries in the car
6) Put weight on the car
7) Run the program
8) After 10 minutes stop the car
9) Take out batteries, and collect data
10) Repeat step 3 through 7 with different weights
Conclusion: When weight was increased, more electricity was used but it didn’t double. For example, when I doubled the weight from 1 pound to 2 pounds there was only a 0.066-volt difference.
Discussion: There wasn’t a huge difference when I increased the weight. Next time, I should make the robot go for 30 minutes instead of 10 minutes or put a heavier weight