A (Different) Perspective on Looking at Physics Formulas
(Muh. Syahrul Padli, Bawah Pohon Science)
Physics is a science with many formulas. Often, formulas appear as terrifying monsters to those who are not familiar with them.
Maybe you are one of them. And that’s okay.
For physicists, formulas are stories compressed into short symbols for making it simple.
The task of those who study physics is to know how to extract these symbols into a complete story about nature. Not only that, but physicists can even develop new and more interesting stories from them.
Perhaps this basic knowledge has been conveyed to us by our teachers in the past in their own language. It’s just that we have forgotten or do not have the capacity to process the information they provided.
But that’s okay.
Bawah Pohon Science is here to remind you again. Or maybe it will give you a different perspective to look deeper?
Let’s start!
Physics is built on precise measurements. That’s why we define quantities.
Quantities are types of quantities that are measured.
The length of a road or track (distance traveled), the length of a table, the length of a book, and “other lengths” are defined as length quantities.
Time is defined as the duration of an event. Or the duration of a change from one state to another.
Measurement is important in physics to obtain precision from the state of an object. In addition, by performing measurements, categorizing what is measured into the concept of quantities, and introducing scales or units, it is possible for someone to make predictions.
A real-world example is when we drive to the minimarket. Under normal conditions, we know that a motorcycle needs one liter of gasoline to go back and forth. With two liters of gasoline, we can predict that we can go back and forth to the minimarket twice.
Liter is a quantity that comes from the measurement of the unit of volume (although it is not a base unit in the International System). One liter is equal to 1000 milliliters.
Liters and milliliters are units. In other words, the scale of the measuring instrument or the indicator of object information. If you don’t have a liter with a liter scale, you can use a milliliter scale beaker. Or, if you want to be precise to half a liter, which would be difficult to achieve with a liter, you can use a milliliter scale beaker until it shows 500 milliliters.
There are many functions of defining quantities and setting the scale of measuring instruments in life. With these two things, we can enjoy online and offline shopping that requires measurements of weight, such as fruit, or length, such as cloth.
Back to the topic!
With two quantities, namely length/distance traveled and time, we can find a new quantity or the derived quantity called speed or velocity or pace.
How is that possible?
Confusing, right?
That’s okay. If you’re not confused, that’s the problem. As long as you are confused and continue to be curious, you will reach new understanding.
One of the basic formulas in physics is speed.
To understand it, we try to use a comparison.
Let’s say Anto and Basri are having a race.
From the measurement information, we finally know the time and distance/length of the track that Anto and Basri traveled.
Anto takes 60 seconds to run 1 km.
Basri takes 30 seconds to run 1 km.
Who is faster?
Basri, right? That means Basri takes less time to travel 1 km than Anto.
In 120 seconds, Anto can run 2 km.
In 120 seconds, Basri can run 4 km.
Who is faster?
Still Basri, right? With the same travel time, Basri can run a longer distance
Because the story of Basri and Anto is too long, we can compress it into a short equation.
How to formulate it is as follows.
We symbolize first.
v as speed
s as distance
t as time
Speed is inversely proportional to time.
In mathematical language:
v ∝ 1/t
Speed is proportional to distance.
In mathematical language:
v ∝ s
We can combine the two equations into one equation.
v = s/t
Oh my God, we get the equation for speed.
Congratulations, you have been able to formulate an equation with only basic logic and understanding.
If you want to analyze the equation, just do the reverse process. Let’s raise the level a bit! Ready?
Almost all moving objects have mass or weight.
Why is there no symbol for mass in the speed equation?
Well, that’s a good question.
The speed formula is actually a theoretical approach. It is an approach that ignores a quantity and focuses on the quantity that is measured.
To adjust to the real world, we need a new quantity, which is momentum. Momentum can be interpreted as the effect of a moving object with its mass.
Let’s say p as momentum. Mass is attached to the object or object. It is attached to the object that is moving at a speed.
Just add it directly. Why? Because the mass for cases in the macroscopic world or everyday life is mostly unchanged. They are relatively constant.
So, if m is the symbol for mass, then the momentum can be formulated as:
p = m v or p = m s/t
Or if you want in another form, it could be like this:
pn = m v1 + mv2 + mv3 + … + mvn
Where vn means momentum at a certain time or distance.
Remember, addition can be converted into multiplication and vice versa. Or if the explanation above is a bit jumping, let’s take a closer look.
Objects or objects that carry mass can be observed from their effects.
For example, a ball that we throw at a pile of cans.
There are two possibilities when throwing a ball at a pile of cans.
Assume it hits the target.
Which one has a bigger effect?
Assume the pile of cans is arranged so that only the ball has an effect.
The heavier and faster the ball, the greater the effect, right?
Compare it to when it is light and not fast.
With that in mind, we can make it into an equation:
p ~ m
p ~ v
So these two equations can be combined to be more concise:
p = mv
Wow, we have formulated two physics equations in one day with basic mathematical knowledge and logic.
More fun, right?
But remember, not all equations can be formulated purely from quantities alone or from logic alone. Sometimes experiments are needed. From the experiment will emerge the name of the constant and some boundary conditions.
Don’t think about that for now.
We’ll discuss it at another opportunity!
