Do you understand how to do physics problems?

Question

If you do, please share with me and all the people like me that feel like we are hitting our heads against a brick wall when we see things like this:

G= 6.67 x 10^-11 N * m^2/kg^2

(go ahead and tell me what that even is, if you know it...)

Just what is the secret to understanding physics math stuff?

Why do you understand physics and mathematics and I don't?

Answer 1

1. First comes interest. You read popular science literature that intrigues you, or watch a science fiction movie and catches your guts shaking when the question of "how the Universe has been created" or "how do hurricanes form and behave" or "what's the basic constituents of matter" and so forth.

This is the UTMOST important step. It is an absolute asset.

2. Then comes energy and will power. You need to force yourself to read that one more chapter in your textbook and understand it and so on. (A good technique is to read the chapter until you hit a place, where you realise that you do not understand what's being said. There, you go back to the beginning of the chapter and start all over. Ideally, you will eventually have read the entire chapter and you have a clear idea of what has been said. This was how Isaac Newton studied Descartes' books. I don't suggest you follow this example, for it is way-way too time consuming, but it gives you an idea of what "reading a textbook" really means.)

3. Then comes knowledge. The more you read, the more things you know about. The more things you know about, the more techniques you can apply at solving a problem or understanding a proof, the more often you can relate what's written to what you already know.

4. Then comes experience. This is very tightly bound to the previous point, but it is yet quite distinct. The more problems you try solving (and look at their solution in case you hit a dead end), the more hints and tricks you understand and bare in your mind. These then are very likely to come up when you'll be solving the next problem.

I believe these basic steps can be done by absolutely anyone, once the first step is achieved. Even if the person is not very bright (I know I'm not), these steps can be done with a large success (may be in a longer time scale).

5. The final step is the wits. Some people were born with wits and are generally very lazy with steps 1 through 4 and hence do not achieve anything until they realise their mistake. Others understand that wits alone will do very little, so (again, given the fact that step 1 is satisfied) they work their behinds off, thinking that "experience and hard work are the only thing that can help me". Little do the know, they develop their wits along this tough road.

As an example, I know I can't rely on my wits, because I have got none (well, some... but very little, believe me). So I know that if I sit down and lay my hands beside, thinking that "I will come with something, no problem", then I better off going cross-country skiing or rock climbing with my fiancee. I realise that I have to work very hard, because there are more than plenty of other guys that are quite a lot smarter than myself, who are working on the same problem. And if I want to have something done, if I want to beat those guys, I need to work extra to what they work.

This is what physics and all of science is like.

Can you understand physics and mathematics the way I do? Sure you can!

Do you want to understand physics and mathematics the way I do? You decide.

Answer 2

The secret is intuition, and it is something that comes naturally to some, but I really believe can be developed in everyone.  What you need to do, when presented with any physics or maths problem is to try to work out exactly what you are being asked.  Before ploughing through any equations, build up the best possible picture of what is going on.  For instance, if asked to calculate the gravitational force between two masses, you need first to work out what a force is.  It is a push or a pull, well, the masses here are pulling each other, and you need to know how strongly.  What affects the strength?  Well, the bigger the mass the bigger the pull, the bigger each mass in fact, the bigger the pull, so you can say that the size of the force depends on the size of each mass, and the bigger each mass the bigger the force, so it makes sense to say that F = m1 X m2 X t, where F is the force, m1 is the size of mass 1 and m2 the size of mass 2, and t is the other factors involved.  The next thing to ask yourself is how the strength of the pull depends on the distnace between the two masses, and the answer is that the further apart they are, the weaker the force.  Experiments tell us that the size of the pull reduces as the square of the distance between them, so we might like to write

F=(m1 X m2)/r^2.  This would be true, except that the units we use (SI) require a scale factor, which is G: F=G(m1 X m2)/r^2.  G is simply the constant value that allows us to use kg for the masses, m for the distance and get and get a result for the force in Newtons.

Always try to picture what is happening!

Answer 3

Notation is evil.  There isn't really anything deep here requiring "understanding."  All it is is some abbreviations that you need to be told about.

10^-11 is ten to the minus 11 power, or 0.00000000001, so the numerical value of G is just 0.0000000000667.

The rest is just units.  N * m^2/kg^2 reads out as "newton-meters squared per kilogram squared."  G needs those units so that when you insert masses in kg and distances in meters into Newton's law of gravitation you get out a force in newtons.

Answer 4

You're going to have a tough time selecting B/A. These are all good answers All I have to add is that it's mostly a matter of interest.

I became fascinated with math and physics when I was a kid and saw the movie "The Forbidden Planet," which later became a major inspiration for Gene Roddenberry, the creator of Star Trek.

One problem, though, ... I sucked,.... big time. Then, in college, BINGO!!! it all came to me and I aced both, hardly needed to study at all.

So, take heart. With a little perseverance and, hopefully, good, caring teachers, it will come to you.

BTW, that was nearly 40 years ago. I'm amazed how much I forgot, but even more amazed how much I remember. I may have lost a few billion brain cells, but I never lost the fascination.

Answer 5

There are 4 primary units:

Mass (g)  grams, Kilograms, etc

Volume (l) Liters, Milli-liters, etc.

Length (m) (meter, centimeters, milli- meters etc

Time (s)  Second, millisecond, etc.

Kilo: 1000 * unit  thus a kilogram is 1000 grams

Centi: 0.01 * unit thus a centimeter is 0.01 meter

Milli: 0.001 * unit  hus a millimeter is 0.001 meter

Lot of other prefixes but those are the main ones.

Everything else is a  combination of those units

Units MUST always balance in a calculation.  If they don't you did something wrong.  It takes extra time and writing, but ALWAYS carry all your units.  They are a check that you did it right.

The G in your question is The Gravitational Constant.  Very important number.  It is used in a very simple equation to calculate the force of gravity between two objects of known mass

N is a derived unit called a "Newton"  in primary units it is:

(1 Kg * m)/s^2)  in words a kilogram times a meter divided by a second square.

Plug it in to G and you get:

6.67 *10^-11 (kg*m/s^2)*(m^2/kg^2)  lot of units but they carried everything like I told you.

The secret is that every thing has units.  How much do you weigh? Say 113.  113 what?  Pounds?  Tons?  You need a unit to make the number meaningful.  Same with all physics.  You need units to.  The units have physical meaning and describe the numbers that go with them.

Best I can  do.

Answer 6

That's the gravitational constant. Constants make our lives easier by telling us the direct correlation between variables. The equation for gravitational force is fg = [G(me)(mo)]/r^2.

As to why I can grasp physics and math, and you can't, it's just something I'm good at. It's unfortunate that so many things in school require a certain aptitude for the maths, but that's the way things go. There are plenty of things you're better at than me (probably social stuff like remembering names and faces, recognizing humor, and avoiding awkward situations). Every human is unique, and this is our species' great strength. We are dependent on other people that have the skills we do not, and they are dependent on us.