Pulley Lab

Objective

The objective of this experiment was to study Newtons second law of Motion: F=ma (Force is equal to mass x acceleration).

Procedure

In this experiment, we used a mechanical pulley to lift a load of a certain mass up against gravity. The pulley was connected to a computer program, which allowed us to exert precise amounts of force on the mass, as well as record its exact acceleration. We lifted the mass a total of 10 times.

The first five times, we kept the force exerted constant. The only variable was the amount of mass being lifted. With each lift, the mass was increased. From this set of trials, we recorded the following data:

Mass (kg)     Acc.                                                                      Chart 1
0.02      85.22
0.06      79.96
0.1        76.85
0.14      69.95
0.18     67.85

From this data, we can see that there is a negative relationship between mass and acceleration. Since the slope of the trend line is negative, we can conclude that as mass increases, a constant force exerted will cause acceleration to decrease.

The second set of 5 lifts was recorded using a constant mass. This time, the only variable was the amount of force being exerted:

Force     Acc.

60          48.11                                                                       Chart 2
50          29.03
40          16.37
30          7.33
20          1.57

In this trend, we see the opposite relationship as the first set of data. Force exerted and acceleration share a positive relationship; this is why the trend line of the graph has a positive slope. The greater the force exerted on a mass, the larger the acceleration.

Conclusion

The relationships that we have gathered from our data does agree with Newton’s second law of motion, Force= Mass x Acceleration. From his formula, we can mathematically see why mass and acceleration must have a negative relationship when the force is fixed. If the equation is to remain balanced, then one value to the right must decrease as the other increases so that they total value does not change. The same evidence is true in the second relationship found. If mass is fixed, then force and acceleration must have a positive relationship in order for the equation to remain balanced.

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