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Question about physics in general, and its weakness

  1. Oct 1, 2009 #1
    (no offence intended)

    I am a Student who excels at mathematics. What i find great about math, is that you can sit in front of a problem and as long as you know basic HS math, you can use you're imagination and logic to solve it.

    HOWEVER, when i sit in front of a physics problem, I CANNOT USE LOGIC, since if i dont know EVERY SINGLE FORMULA and physical sciences knowledge, its impossible for me to solve it.

    For example: if there is x+3x2+dx+C (not a real probleM), I could go 1- factorize, 2-isolation of x 3-split to two formulas and plug in points 4- Use various theorems, 5- draw a graph using zeros and summets 6-draw a graph using a simple table 7- ect..........

    But for a physics problem: Automobile experts will oftentimes refer to a car's "0 to 60 time", the time it takes for a car to go from rest to 60 miles/hour, when talking about how powerful its engine is. For example, a Ferrari Daytona's "0 to 60 time" is about 6 seconds.


    a.
    What is the acceleration of this car compared to that of gravity?
    b.
    If you had a car able to accelerate at 1 g, what would its "0 to 60 time" be?

    IF I DONT KNOW the a=deltaV/deltaT and the 9.8m/s2 gravity of earth, and blah blah blah blah blah I wont solve it.


    Or is physics just the memorization of hundreds of formulas and of hundreds of laws and then applying them?
     
  2. jcsd
  3. Oct 1, 2009 #2
    WHY is physics like this

    (no offence intended)

    I am a Student who excels at mathematics. What i find great about math, is that you can sit in front of a problem and as long as you know basic HS math, you can use you're imagination and logic to solve it.

    HOWEVER, when i sit in front of a physics problem, I CANNOT USE LOGIC, since if i dont know EVERY SINGLE FORMULA and physical sciences knowledge, its impossible for me to solve it.





    For example: if there is x+3x2+dx+C (not a real probleM), I could go 1- factorize, 2-isolation of x 3-split to two formulas and plug in points 4- Use various theorems, 5- draw a graph using zeros and summets 6-draw a graph using a simple table 7- ect..........

    But for a physics problem: Automobile experts will oftentimes refer to a car's "0 to 60 time", the time it takes for a car to go from rest to 60 miles/hour, when talking about how powerful its engine is. For example, a Ferrari Daytona's "0 to 60 time" is about 6 seconds.
    What is the acceleration of this car compared to that of gravity?
    If you had a car able to accelerate at 1 g, what would its "0 to 60 time" be?

    IF I DONT KNOW the a=deltaV/deltaT and the 9.8m/s2 gravity of earth, and blah blah blah blah blah I wont be able to solve it, no matter how intellectual/logical i am.






    Or is physics just the memorization of hundreds of formulas and of hundreds of laws and then applying them?
     
  4. Oct 1, 2009 #3
    Re: WHY is physics like this

    Not at all. All of physics is based on a few very simple principles which in turn can lead to some very complicated formulas. The formulas had to come from somewhere though, and all of them except the absolute most fundamental can be derived using math. Physics is basically just applied math. No one out there memorizes all the formulas, but rather physicists usually remember them simply from using them so much.

    Think of physics as complicated word problems in math. They can all (almost all anyway) be solved by applying basic principles and deriving equations to suit your needs. It really isn't as different from pure math as you would think.
     
  5. Oct 2, 2009 #4

    G01

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    Re: WHY is physics like this


    Yes it is more then that. Take it from someone in grad school for physics. Someone whose plan to learn physics is to memorize tons of formulas and blindly use them will never become a physicist.

    Memorizing formulas is a huge misconception. That is not how you learn physics or become a good problem solver. It will never help you learn physics. In real physics, you apply fundamental concepts to a physical situation and use them to quantitatively describe a situation or solve a problem.

    I have a feeling this post was written out of frustration. Don't give up. Physics requires a unique form of thinking that you may not have used before in other subjects. Even people who a good at math may at first be thrown for a loop by physics. Give it a chance and keep at it.

    Those "hundreds" of laws and formulas were actually derived using some of the most brilliant logic and reasoning and experimental methods ever devised. Maybe if you give the subject a chance, you will be in it long enough to see this for yourself.

    You should learn to become aware of your severely limited experience in a subject before passing judgment on it.
     
    Last edited: Oct 2, 2009
  6. Oct 2, 2009 #5

    Born2bwire

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    Re: WHY is physics like this

    Of course it has to be this way. If it was too easy then anybody could do it, we have to protect our phoney-baloney jobs, you know.

    Although I assure you that high school mathematics does not get you very far in solving mathematical problems. Vector calculus, multivariable calculus, differential calculus, linear algebra, discrete mathematics, boolean algebra are all examples of topics beyond high school that are necessary knowledge to solve most mathematical problems of any consequence in the sciences, engineering, or mathematics of today.

    And as for physics, there generally are very few equations that you really need to know. For the most part, you can derive, via mathematics and logic, most equations in physics from basic first principle relationships. For example, practically the entirety of electrodynamics and electromagnetics comes from five equations, the Lorentz force and Maxwell's equations. The only other real branch that is left out is the effects of special relativity, although Maxwell's equations follow special relativity and thus you can derive the Lorentz contractions and relativity from the principles of Maxwell's equations (as was done historically).
     
  7. Oct 2, 2009 #6

    Vanadium 50

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    Re: WHY is physics like this

    Born2bwire Johnson's right!

    Exactly. Here's a classic example from 1696 - "Find the shape of the curve down which a bead sliding from rest and accelerated by gravity will slide (without friction) from one point to another in the least time." Any high school student can understand it - but it takes more than high school math to solve it.
     
  8. Oct 2, 2009 #7
    Interesting post. What I find great about physics is that you can sit in front of a problem, and if you don't know a formula to solve it you can find one through experimentation and observation. Think Newton and the apple.
     
  9. Oct 2, 2009 #8
    If you don't know that the infinitesimal rate of change of some coordinate with respect to the variable it is dependent upon is the derivative of that coordinate with respect to that independent variable, how can you even claim to understand mathematics?
     
  10. Oct 2, 2009 #9
    Re: WHY is physics like this

    Hmm, I see you have two posts. Didn't see this one before I posted in the other one.

    Interesting post. What I find great about physics is that you can sit in front of a problem, and if you don't know a formula to solve it you can find one through experimentation and observation. Think Newton and the apple.
     
  11. Oct 2, 2009 #10

    russ_watters

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    Agreed, I see physics exactly the opposite way from the OP!

    My biggest two intellectual weaknesses are memory and attention span. The memory problem makes it impossible for me to memorize piles of formulas or long methodologies, which presented me with some difficulty depending on the methods of some of my teachers. In physics, though, I would often just memorize a few key equations and if I got in trouble, I'd just derive what I needed from them!

    Ie, the car problem is a perfect example of exactly the type of problem where I used to do that. You only really need to learn one equation for it: f=ma, and one fact (the value of g).

    You don't need to memorize that a=dv/dt because that equation is contained in the units of acceleration. Same for speed vs distance. You can easily derive the equations you need to solve most high school Newtonian motion problems using only that one memorized equation.

    Ie...

    c. How far did the car go as it accelerated from 0-60?
    d. The car has a mass of 1000 kg - what's the force required to accelerated it from 0-60 in 6 seconds?
     
  12. Oct 2, 2009 #11

    russ_watters

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    Re: WHY is physics like this

    Don't double post. Thread locked.
     
  13. Oct 2, 2009 #12

    minger

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    I can teach you every single physics principle that you'll ever (on Earth at least) need:

    Conservation of Energy
    Conservation of Momentum
    Conservation of Energy

    Applying them though can often times require a lot of math.
     
  14. Oct 2, 2009 #13
    This is an interesting observation from which to express one of my observational theories, that in this respect, there are two basic types of people, which I define as follows:

    The "Concept Builder", or the person who strives to find or formulate defining relationships from which to explain what goes on around us. These people try to define, wherever possible, the relationships behind whatever occurs around them.

    The "Process Follower", or the person who seeks to learn and remember the processes and related environmental rules and factors that govern everything. Everything requires a set of these defined rules, to determine what is to be done or what is occurring.

    We all have both characteristics; but which predominates defines which type we all are. A few exceptional among us are strong in both areas (but not many - - not myself).

    Process Followers make the best bureaucrats, for example - - as long as they are not "Peter Principled" into positions in which derivational and imaginative new approaches are required.

    Engineers should ideally be Concept Builders, but this is not always possible. Often imagination is discouraged when it threatens the established culture, and engineers themselves sometimes are more Process Follower than Concept Builder.

    (Maybe this should be a topic of its own.)

    KM
     
  15. Oct 2, 2009 #14
    Not true.
     
  16. Oct 2, 2009 #15

    Redbelly98

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    Physics students who approach it as a bunch of formulas to be memorized generally do really badly at it.
     
  17. Oct 2, 2009 #16
    But there is a lot more to math than this. If every mathematical problem came down to high school math and simple logic we would have proven the Reimann Hypothesis by now.
     
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