Image Source: Crane – LabVIEW for Lego MINDSTORMS Projects

Our second experiment on robotics evolved around Newton’s Second Law of Motion, which states that force in Newtons is equal to mass (Kg) x acceleration (m/s2). For this experiment, our NXT Lego motor was attached to a string that was placed on a pulley to raise slotted weights. Here, we tested the acceleration in which the weights got pulled, as we changed the mass of the slotted weights and the force the motor would use.

First, we tested the acceleration according to the mass on the slotted weights. We found that with the power level fixed at 75%, as the load increased, the acceleration decreased, and the same would happen when vice-versa.

Next, we tested the acceleration by changing the power level but maintaining the weight steady. We found that by increasing the power level, the acceleration would also increase, and by decreasing, the acceleration would also decrease. At the same time, by testing different power levels, my partner and I were interested in testing the limits of the pulley. We found the 127% was the maximum power level in which the pulley-operated, and 40% the minimum power in which the pulley retrieved the weights. When we tried setting the pulley to a power level of 500%, however LabView would automatically set it to 127%, and as we attempted a power level lower than 40%, the pulley would only pull the weights up to a certain height and then would stop.

Our next two tests for this experiment evolved around the laws of conservation of energy based on our previous experiments. We measured the battery discharge in voltages (mV) through LabView as we changed the mass of the weights and estimated the energy generated in joules (J) by multiplying the mass (Kg) times gravity (9.8 m/s2). As seen below, as the battery discharge increased, as the potential energy also increased.

Lastly, we analyzed the relationship between Power level (%) and Power (Watts). We calculated Power (Watts) by using the equation: Power = We found that the power level and power had a proportional correlation, as the power increased whenever the power level increased.

In conclusion, through this experiment, we were able to see Newton’s Second Law of Motion in action and understand why energy cannot be created nor destroyed. We saw that by increasing the power of the motor, the power being released also increased. Simultaneously, we noticed that if we raised the mass of the weights, the motor required more power to have a similar acceleration to the load with a lower mass. Lastly, we understood that the energy the pulley generated when it lifted the wights was never destroyed, as it transformed into heat which was then released to the air.