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I've been reading some Feynman's books. There's a point that intrigues me. It's the fact how we understand a physics equation, not only mathematically, but digging deeply into its roots as a physicist. I'm just a first- year- physics student, but I would like to understand the basic equations I'm studying through its physical meaning, but to be honest I don't really know what Feynman meant. I hope you can help me. For example a equation such as:

F=ma

Thanks!

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    $\begingroup$ So this might be more advanced than the level you are looking for, but check out this question and answer about techniques for understanding equations. Once you start to get a feel for what kinds of terms appear in physics equations (even something like $F = ma$ is a differential equation), you can start to wrap your head around connecting the sometimes-complicated math to the physical world. $\endgroup$
    – tpg2114
    Commented Jul 16, 2015 at 2:50
  • $\begingroup$ Thank you!I think it was what I was looking for. It's kind of advanced, but I get the point :D !! Thanks! $\endgroup$
    – Omar
    Commented Jul 16, 2015 at 3:08
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    $\begingroup$ As @Alex's answer recommends, it's best to start thinking about the cause-effect in the physical world around you and what those things would look like in equation-form. And like my answer on the other question says, it helps to look at the equations and try to identify what they represent in the physical world. Start simple and small and start building up that logic/intuition! $\endgroup$
    – tpg2114
    Commented Jul 16, 2015 at 3:10
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    $\begingroup$ Understanding an equation means you must have an idea how the solutions look like without actually solving the equation. What it means to be understanding an equation physically you will learn that from experience anyway,just keep reading Feynman. $\endgroup$
    – Paul
    Commented Jul 16, 2015 at 4:41

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To work with F=ma physically, just imagine how it plays a role in your daily life. As you rise from bed you are exerting a force on the bed accelerating your body up to a point where you say to your self, just kidding and then sleep in! Physics can be fun, don't let anyone trick you into thinking its a serious subject for serious people. Feynman knew this best.

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    $\begingroup$ Yeah!I do that!. Physics is way fun :D from the very moment I wake up to the time I sleep :D. $\endgroup$
    – Omar
    Commented Jul 16, 2015 at 3:06
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It's helpful to look at an equation about think about what it can tell you. For instance, if you know that total net force, and the mass, then you can find the accelerations (a=F/m), so this can predict motion.

Similarly if you know the acceleration and the mass you can find out the total net force (F=ma)

Or if you know the force and the acceleration you can find out the mass (m=F/a). That's already three things you can do with the one equation.

But since it is supposed to be a universal law you actually learn more. For instance the mass an object had that worked in F=ma for some particular force is the exact same mass that appears later or earlier or when there are different forces. So the point is that you could use a known force and measure the acceleration on Monday and find the mass then use that same mass (from Monday) and measure the acceleration on Tuesday to learn about the forces on Tuesday. So you can use those three different ways at different times to learn about masses and forces.

So it's actually saying a lot, it's saying that there is a thing called mass that works on all those different days and that it has the same values on those different days. It says that the same value of mass works for every possible force as well as for every possible location and every possible time.

And by using it to learn about forces there are many things that you can learn about forces. You can learn what makes each force have the values it has. You can learn how different forces combine into a total force. You can notice that forces make thing one and thing two have different accelerations, but that there is something the ma that is the same. And once you find regularities in a force, you can make additional laws to codify the other things forces do. Such as coming in action-reaction pairs.

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