The purpose of the pulley experiment was was to explore Newton’s second law, the conservation of energy, velocity, acceleration, and power.  Newton’s second law states that the acceleration of an object is dependent on the net force acting upon an object and the mass of an object.  In 1842, Julius Robert Mayer discovered the Law of Conservation of Energy.  This law states that energy is never created nor destroyed.  This means that in any scenario energy is never ‘lost’, but simply transferred to another form of energy.  In this experiment we used a Lego Mindstorm motor and a pulley to lift weights to measure power and acceleration.  Through the application that we used on the computer, we were able to change the power of the motor and also calculate the acceleration that the weights ascended.

 

The apparatus that was used for the experiment was a pulley, a motor, and weights that measured up to 250 grams.  The motor was attached to the base of the pulley system.  A rod held the pulley about 12” above the motor, and a string was attached to the motor ran over the pulley and was connected to the series of small weights.  The apparatus is shown below.  

 

During the first half of the experiment we were testing Newton’s second law.  We did five separate trials to measure the acceleration of the weights.  We kept the power at a constant of 50 and did five trials with different weights varying between 0 grams and 250 grams.  Because the how the computer application was set up we had to consistently convert grams to kilograms to get accurate results.  By looking at the data we collected from the five different trails, we can see that we have confirmed Newton’s second law.  As we increased the mass and kept the power constant, it can be seen that the acceleration of the mass diminished as the weight increases.

 

MASS(KG)                       POWER                     ACCELERATION(RPM/S)

0.25                                       50                                   10

0.09                                       50                                    21.74

0.13                                       50                                    20.8

0.15                                       50                                    18.75

0.19                                       50                                    14.25

 

During the second half of the experiment, we ran the trails nearly opposite.  We kept the mass constant while we increased the power level and examined the acceleration.  As we increased the power of the motor, the acceleration of the mass continued to increase which would make sense when comparing the data to the first half of the experiment.

 

MASS(KG)                       POWER                     ACCELERATION(RPM/S)

0.25                                       45                                   6.58

0.25                                       55                                  13.93

0.25                                       60                                  19.42

0.25                                       70                                   32.85

0.25                                       85                                   57.67