In the realm of physics, every motion in the universe is governed by a multitude of forces. From the smallest subatomic particle to the gigantic astronomical body, each particle follows a universal law of forces that determine how they interact with one another. Understanding how these forces work is essential in understanding how the natural world around us works, and then to subsequently apply that knowledge to develop the human race in general.
Some forces are readily observable and felt by people around us; some are not. Three of the most prominent forces affecting our everyday lives are the pressure gradient force (PGF), the Coriolis force, and the frictional force. In this lab report, these three forces will be indirectly observed and analyzed to be further understood.
Pressure Gradient Force (PGF)
As it name implies, pressure gradient force is the force that is generated by a difference in pressure from one area to another. One naturally occurring pressure gradient force that can be readily felt around us is the wind. Wind is caused by air moving from an area of a higher temperature from an area of lower temperature (Hewitt).
In the laboratory exercise, we were asked to observe the nature of the wind. Since wind is practically invisible, it can only be observed indirectly—flags waving, trees fluttering, gusts blowing, curtains flapping, among others. For my observation, I picked the twilight of Sunday, July 10. The weather was chilly, and there was a slight gust of wind blowing. The effects of the wind are evident in the rustling of the leaves—the wind was not strong enough to slam doors, but every now and then a gust of wind would come in the open window when one is indoors, making the temperature seem colder than it really is.
Based from my observations, there was no specific direction from where the wind is blowing; if there were, it would not be readily observable given its very slight effect on the objects in the environment. The wind was slow in general; however, it fluctuates. At times it would only be a gentle breeze, other times it would be forceful, but for the most part there was no wind at all. According to the news, the wind was caused by a monsoon, which is then caused by changes in temperature. Since temperature is directly proportional to pressure, it can be said that wind blows from an area of high pressure to a low one.
Coriolis Effect
The Coriolis force is an example of a rotational force—the force that acts upon a rotating object. There are two famous kinds of rotational forces: the centrifugal and the centripetal force. Centripetal force if a force that causes a moving object to go towards the center of a rotation and is classified as a real force, while a centrifugal force is the force exerted by an object to stay away from the rotational pull of the centripetal force and is classified as a fictitious force (Hewitt).
The Coriolis force appears differently from the one observing it and the one experiencing it. For an example, I will use an incident wherein a passenger sits on the edge of a vehicle that is about to go in a roundabout. As the vehicle approaches the roundabout, the passenger involuntarily tilts his body away from the perceived center of the roundabout, and thus he may conclude that it is the Coriolis force, at hand.
An outside observer, however, would look at the situation differently. For the observer, the passenger is trying to follow a linear path away from its rotational direction, and can be chalked up to the passenger trying to tend to stay in motion in a path where he is first led to—a variation of the third law of motion.
Frictional Force
Unlike the other forces described above, frictional force is different in the sense that it resists motion instead actively propagating it. When there is motion involved, friction also plays a part as well—without friction, motion would not be effectively stopped (Hewitt).
For the experiment, I chose to run in the early morning of July 11. There was a little amount of wind, so I decided to run and feel how the wind brushes off against my body. Since my body generates friction in the wind as I moved through space, then I can observe how it interacts with my body so as to get a glimpse of how friction works.
For the first few minutes, I was not moving too fast, so it can be said that the friction against the wind is relatively light. There was some resistance felt, but it was barely noticeable. However, as I increased my running speed, there was an active sensation of the wind brushing off against my body With that said, I can infer that frictional force is directly proportional to the amount of force generated—the greater the amount of motion, the greater is the amount of friction involved as well.
Work Cited
Hewitt, Paul. Conceptual Physics. London: Pearson. 2014. Print.
