Projectile Lab Essay

How Does a Projectile Object Demonstrate the Law of Conservation of Energy?

The purpose of the projectile lab is to test the validity of the law of conservation of energy. The application of this law to our everyday lives is a surprisingly complicated process. Conservation of energy states that energy cannot be created or destroyed, but that it can be transferred from one form to another. Consider the projectile lab from document A that this essay is based upon. In an ideal experiment, the projectile is isolated from everything except the gravitational field. In this case, the only force acting on the particle is gravity and there are only two forms of energy that are of interest: the energy of the particle due to its motion (defined as kinetic

As a simple case, consider the simulation of document . In the frictionless case, the only force acting on the skater is gravity. Therefore, according to the conservation of energy, the sum of the kinetic and the potential energy remains constant. As the skater climbs the ramp, his height increases. According to document , as the skater’s potential energy is proportional to his height, the skater’s potential energy increases. However, the skater’s velocity also decreases as he climbs the ramp. Again, according to document , as the skater’s kinetic energy is proportional to his velocity squared, the skater’s kinetic energy decreases. The interplay between these two energies is such that their sum remains constant and the law of conservation of energy remains

From the bar chart, we see that the potential energy in general agrees with the case above, i.e. it increases up to the particle’s maximum height and decreases from that point on. The kinetic energy, on the other hand, behave significantly differently than expected. Rather than decreasing form the beginning to the maximum height and then increasing, the kinetic energy appears to fluctuate in a somewhat random manner. This can be best understood by treating the experiment as a closed system, where energy (but not mass) can leave the system and enter the surroundings. As the projectile moves through the air, it collides into air particles, imparting some of its energy to these particles in the form of friction, heat and sound, thus losing energy in the process. We therefore would expect the sum of the potential energy and the kinetic energy to decrease over time as the projectile loses energy to its surroundings. However, from the data from document , this also does not seem to be the case. This discrepancy can be explained by including experimental uncertainty, where errors in our measurements can lead to unjustified conclusions. In order to reduce the sources of these errors, the experiment should be run multiple times in ideal conditions, averaging over the results and calculating the resulting averaged energies.

In summary, the law of conservation of energy does indeed hold true. In