The fast-paced nature of today’s society has led many people to actively streamline their various activities throughout the day, which can save them anywhere between seconds to minutes of valuable time. This may not seem a lot at first glance, but they do add up and can make a difference. A common example takes place during commute, wherein some would step off the bus or train as soon as the doors opened even when the vehicle is still in the process of slowing down to a complete stop. If you’re not careful, doing this relatively simple manoeuvre may have left you off balance and gave you a little scare. And believe it or not, there’s some interesting science behind this rather impatient way of disembarking that we’ll get into more detail below.
It All Starts With Inertia
As a refresher, our old friend inertia from O-Level physics is the property of an object that resists or opposes change to its motion. Hence, it can be thought of an object’s “laziness” in a way. Therefore, in a vacuum free of air resistance and friction, anything that gets set in motion will keep moving indefinitely unless something stops it. Alternatively, an object will remain as still as stone until an external force gets it going.
What Is A Frame Of Reference?
Simply put, this vital concept can be thought of as a window through which we observe the physical processes and various phenomena around us. A good way to think about this is through an example: you’re inside your home and your parents ask you to check on your siblings who are playing outside. You then go to the window to look, which serves as your reference that lets you determine things like how far away your brothers and sisters are and how fast they’re running around.
If you can recall from your early physics tuition classes, this window or frame of reference consists of scales that provide us with useful coordinates. Fully comprehending a physical process with high accuracy requires one to look at it from a single point or ‘origin’ as well as a set of rulers or ‘coordinate axes’ with which to measure the system’s movements. Together, this origin and coordinates make up our frame of reference, which are categorised into two main types–inertial and non-inertial.
As you may have guessed, a frame of reference can be mobile or at rest. Specifically, both types are on the move, with the main difference being that an inertial frame is travelling at a constant speed while a non-inertial frame features some acceleration. Whenever we encounter an event in our daily lives, we serve as the frame of reference by being an observer, and we don’t actually need a literal scale to measure things. All our experiences are based on our frame of reference, and the same incident may be experienced by another person in a different way since their frame of reference differs from ours.
All in all, the important thing to keep in mind is that we’re always acting as a frame of reference whenever we sit, walk, run, jump, or do anything else. Going back to the initial phenomena about getting off a moving vehicle, we are essentially in its frame of reference, and it is what causes us to lose our balance.
A Fictitious Force
As discussed earlier, objects only move if they are subjected to external forces. So, when we’re riding a car and the driver suddenly floors the brakes, we consequently jerk forward. The same happens when we alight from a running train, for example, and we get shifted backwards upon landing on the platform. At this particular moment, our motion is changing and yet there is no direct force acting on our body. You may be asking, then, what exactly is causing our loss of balance? The answer is a fictitious force.
This force acts on us whenever we switch our frame of reference, such as in the case of transitioning from a mobile frame of reference like a moving bus or train to a stationary one such as the sidewalk or train platform. It also occurs anytime a frame of reference is non-inertial, like during the immediate deceleration of a braking car.
Conclusion
Whether it’s losing one’s balance when stepping off a moving bus or something else, there’s plenty of everyday happenings that have surprising physics behind them. This just goes to show how physical principles subtly impact all our daily experiences—even in moments as ordinary as hopping off a bus or playing a guitar.
Tuition Physics is the place to discover more about these interesting principles, how they apply to your everyday experiences, and enhance your problem-solving skills to excel in physics and beyond. Sign up for our tuition classes today and learn what’s behind our proven track record of success.
