I understand that F=ma, mass is in kilograms and acceleration is metres per second squared so Newtons are just kilograms metres per second squared, but what does that mean? I can’t seem to comprehend it/really understand it intuitively. Why are we adding kilograms, metres per second squared times (or vice-versa)? I understand stuff with division, like density, because it makes sense, like with density, you’re dividing the mass over the volume occupied to see how many kilograms you have per cubic metre of the substance in question, so kg/m^3 , but I seem to have trouble understanding the multiplied quantities, like Newtons.
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It’s hard to explain because when it ‘clicks’ the difficulty becomes forgotten.
In your case I think you are overthinking rather than under thinking.
Look at the first equation: F=ma.
Force is what we call matter (mass) as it is accelerated. Does that make sense? If so hang on tight to that. We are going to add the rest to it.
So we need a way to describe mass. Si is pretty set on grams and kilograms so let’s just go with them. In fact, we are building machines for ants so we are going to just stick with kilograms.
Next part is where it gets a little tricky. Acceleration is a change in velocity. Let’s say how much it changed in a second. So acceleration is (change in velocity) ‘per’ second also written as (change in velocity)/second. But velocity also has a term. We list it in meters per second. So acceleration is really (meters per second per second) Or switching that to our more mathy view, meters/sec/sec. And since that’s a lot to write, let’s just say meters/sec^2. The velocity and change in velocity are in the same second so it is logical to square up.
So now that we built the ‘m’ and ‘a’ parts, let’s put them together.
Force is mass times acceleration. Force is (kilograms, a measurement of mass) times (m/s2, a measurement of acceleration).
Force is kg • m/s2
Just walking through the steps and ideas demonstrates how we arrive at the kg•m/s^2. We just put in base units from velocity to acceleration to time up to Force, which a derived unit. We get a somewhat unwieldy term. So someone created Newton.
My hardest concept (still) is ‘how is there no force if there’s no change in velocity. I mean, I’m pushing pretty hard on this building, how are you telling me there’s no force?
Anyway I probably put too high an expectation on five year olds and someone probably did a better job by now. Good luck.
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