Welcome to part 2 of our exploration into the Interconnection of Physics. Here, we will explore some fascinating connections across surprising Physics concepts. If you haven’t already, make sure to read part 1 of the exploration, especially because this part takes a leap over the introductory concepts and exposes some university content. Without further ado, let us explore three more awesome interconnections in Physics!
4. Linear and Rotational motion
As their names suggests, linear motion is translational, meaning that the object physically moves in a certain direction, and rotational motion is based on rotations, where the object itself is rotating about an axis. To create a visualization, imagine that you are driving a car. The car is translationally moving in whatever direction you wish, whereas the wheels are rotating about the axle (that rod that connects the center of the wheels in the back or in the front). Therefore, the car is physically undergoing linear motion and its wheels are experiencing rotational motion. Another example would be Earth, where we are orbiting the sun (though it is circular motion, we are still translationally moving), and rotating about our own axis (which is responsible for our day and night cycles).
Although these are two different kinds of motions, they are very closely related in terms of the Physics formulas. In fact, their formulas between many other concepts, like kinematics, forces, momentum, and energy, essentially have the same structure, just with different symbols (of course, to differentiate between linear and rotational calculations). Besides the actual content, the difference between the linear and rotational motions is that rotational motions concerns the radius of the object. Because rotational motion is university content and can be confusing, the important thing is that the similarity between the formulas reveals that these everyday motions still fall under the universal laws of Physics, especially Newton’s laws.
5. Waves and Springs
Diving deeper into the more theoretical parts of Physics, waves are recognized as a disturbance in a medium that carries energy without moving particles and springs are a medium that can push or pull an object. The connection between these two would be the concept of oscillations, which are referred to repetitive movements (without an external assistance).
Generally speaking, waves have an amplitude (power) and a wavelength (distance between two successive waves). A couple examples of waves are sound waves and electromagnetic waves (includes infrared, visible light, and x-rays). Oscillations occur in waves because these amplitudes and wavelengths are constantly repeating one another. This explains why we usually experience a constant amount of light from the sun; the waves do not change in power or frequency.
When it comes to springs, there are compressed springs and expanded springs. Compressed springs result from objects compressing springs beyond their equilibrium point, and expanded springs have objects pulling springs from that point. For springs, when the spring is allowed to expand or compress back to their equilibrium point, their energy and momentum make it so that they pass that point, compress or expand again, pass the point again, resulting in a repetitive, oscillating motion.
This unexpected connection into oscillation infers that the energy and momentum between waves and springs are the same, allowing them to follow their own repetitive pattern. Along with that, the applications of oscillations include musical instruments (strings can act as waves), alternating current, and understanding the beating of the heart (just imagine that a point in the spring example creates a heartbeat).
6. Stars and Time
Stars, those large, bright celestial bodies that shine high in the sky, and time, a measurement between two events. It takes time for its emitted light to travel around. Did you know that the stars that we see in the night sky had been dead for such a long time? Yet we believe it is still there because the light is just reaching us now. This not only justifies that stars are astronomically far away, but also that the speed of light is constant.
Because speed depends on distance and time (from the formula, v = d/t). If the speed is constant, then the only variables that could change would be distance and time (ex: 4m/s can be calculated with either 4m ÷ 1s or 12m ÷ 3s). We had just seen the star’s effect on time, but this formula reveals that they affect distance.
Imagine a star releases a certain wavelength. A Physics concept, known as the Doppler Effect, suggegs that if the star is in relative motion compared to Earth, we measured that wavelength differently. Referring back to that v = d/t formula, we had just seen that time changed; the distance, which is the wavelength, must also change. If you recall hearing the terms, red-shift and blue-shift, then this is where it came from. Red-shifts are evidence that the star is moving away from us, whereas blue shifts are for stars moving closer to us.
Of course, Einstein’s theory of special relativity is directly connected between stars and time, especially because stars can move close to the speed of light. Though his theory itself is fascinating, the application of it is confusing. Therefore, it is at your discretion to find this connection yourself.
Closing Statement
Congratulations on making it to the end of this series! Of course, these six connections are amongst an astonishing amount of connections and applications. We have explored through quick glimpses of the high school Physics content with sprinkles of some university content. Remember, each connection progressively became harder to understand and more reliable on imagination and application. However, what makes this amazing Physics journey possible is that almost every time, everything is held under universal laws. The consistency and interconnection of Physics makes the world make more sense.
