# Classical physics Definition and 61 Discussions

Classical physics is a group of physics theories that predate modern, more complete, or more widely applicable theories. If a currently accepted theory is considered to be modern, and its introduction represented a major paradigm shift, then the previous theories, or new theories based on the older paradigm, will often be referred to as belonging to the realm of "classical physics".
As such, the definition of a classical theory depends on context. Classical physical concepts are often used when modern theories are unnecessarily complex for a particular situation. Most usually classical physics refers to pre-1900 physics, while modern physics refers to post-1900 physics which incorporates elements of quantum mechanics and relativity.

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1. ### Crosswind problem (pgs. 34-35, Thinking Physics, 3rd edition)

Hi everyone, I was looking to develop my physical insight when I encountered this book by Lewis Caroll Epstein. For the crosswind problem, I couldn't understand the author's explanation; in particular, his concept of "artificial wind," and the force being larger in this case than the previous...
2. ### A Does the theory of information have anything to offer for physics?

Is there any use for this concept in classical branches of physics? Can it be of any help for a physicist in resolving problems (or, at least, in resolving them more efficiently when compared with traditional methods)? The word «classical» means exactly that, i. e. mechanics, hydrodynamics...
3. ### Application Of Kirchoff Law (Desert)

Homework Statement:: Sand is rough and black so it is a good absorber and radiator of heat depending on temperature. During the day, sand's radiation of the sun's energy superheats the air and causes temperatures to soar. But, at night most of the heat in the sand quickly radiates into the air...
4. ### Roundtrip by Plane

The question I have is that if the aero plane is traveling in the same direction as the wind, would it not increase its velocity, as in with boats and streams? So, if by chance, ##w = v##, then the velocity of the aero plane would double. It feels weird as going by the same logic, if the speed...
5. ### Projectile Intercept Math & Trigonometry

Looking for some guidance on how to set up the equations for a projectile intercept given that you have perfect information about the target velocity, size and weather conditions in a 3D scenario, it's for an amateur videogame that I'm developing in my spare time For simplicity sake let's...
6. ### Is there some geometrical interpretation of force from Newton's Laws?

dP = F dt dE = F dr or if we introduce ds = (dt, dr) (dP, dE) = F ds And both dP and dE are constant in closed system. Some questions: - How does its implies on definition of Force? - Is there some clever geometrical interpretation of Force? - Why P and E seems almost interchengable?
7. ### Potential Gradient for individual charges and parallel plates?

In my book, the potential gradient for a charge placed anywhere in space is defined as: E = -V/r HOWEVER, for parallel plate (capacitors) the potential gradient is defined as E = V/d (V being the potential difference). How come there's no negative sign for the potential gradient of the parallel...
8. ### Runge-Kutta Projectile Approximation From Initial Conditions

Hi everyone. I'm a new member, great to be here:) I have a few questions that I wanted to ask you guys regarding the method by which we implement the Runge-Kutta approximation of Projectile Motion if we should do it using a numerical iterative method with a Spreadsheet like Excel. I have...
9. ### Constraints in Rotation Matrix

In Rigid body rotation, we need only 3 parameters to make a body rotate in any orientation. So to define a rotation matrix in 3d space we only need 3 parameters and we must have 6 constraint equation (6+3=9 no of elements in rotation matrix) My doubt is if orthogonality conditions...
10. ### Are electric circuits considered as electrostatics or electrodynamics?

Thanks in advance!
11. ### What is the minimum velocity needed?

I tried to solve this problem and this is what I could come through: When the object is moving, the force acting on object is the frictional force, so, it got to be μmg. So, F = ma and as F is μmg μmg = ma μg = a So, to find out the magnitude of the initial velocity v given to the smaller...
12. ### How to find the equilibrium point between two masses? (Topic 6.2)

Morning all I've recently come across a problem where I get conceptually but cannot apply mathematically if that makes sense. I understand the position of the third mass must be at the equilibrium point of ##m_1## (##9.0×10^{24}kg##), so ##\Sigma F = 0## right? And not even necessarily zero...
13. ### I How does Classical Physics explain Quantum Entanglement?

As a Computer Programmer, it's hard to wrap my head around Quantum Entanglement and non locality being explained in the context of Classical Physics. In other words, if the universe at it's core is physical where does Quantum Entanglement fit within a physical picture of reality? There's been...
14. ### I Distribution of particles

I'm reading Mechanics by Landau and Lifshitz, chapter IV, and trying to understand how in a (closed) center of mass system, with randomly distributed and oriented particles that disintegrate, "the fraction of particles entering a solid angle element ##do_{0}## is proportional to ##do_{0}##, i.e...
15. ### I Radius vector in cylindrical coordinates

I am starting to learn classical physics for my own. One exercise was, to calculate the vector r (see picture: 1.47 b). The vector r is r=z*z+p*p. I don’t understand this solution. My problem is: in a vector space with n dimensions there are n basis vectors. In the case of cylindrical...
16. ### Solve for x(t) and v(t) given a Force equation using Mathematica

Homework Statement Homework Equations F= ma or F= md^2x/dt^2 The Attempt at a Solution I know that this second order differential is non linear. I attempted to solve the problem as -k/x^2 = md^2x/dt^2 but I'm getting trouble since it is a second order ODE and I haven't learned how to solve...
17. ### Scleronomic or Rheonomic Mechanical System?

I would really appreciate if someone could advise me whether the system below is a scleronomic or a rheonomic mechanical system, or a mix of both. If we consider the first pendulum, the constraint is fixed which leads to a scleronomous case while the constraint of the second pendulum is not...
18. ### Classical Searching for Books with Difficult Problems (especially electricity and elecromagnetism)

Hi! As the title suggests, I am searching for some good problem books with really challenging problems for classical physics, more precisely on the topics of electricity and elecromagnetism, geometrical optics and wave optics, thermodynamics and analytical mechanics. When I say challenging I...

24. ### What's the most effective way to study/learn physics?

Ive always been fascinated by the subject, and i absolutely love learning new concepts, especially when theyre intriguing and brain-twisting, but i can never seem to grasp onto the depths of concepts for a long time. Suppose, if i stop working out problems for a week or so on a particular...
25. ### Potential ##V## and potential energy ##E_{pot}##?

Hi, I know that in an elecric field the potential energy ##E_{pot}## is equal to the potential ##V## times the charge ##E_{pot}=q V##. Here my problem: I know that the potential energy of a spring is ##E_{pot}= \frac{1}{2}kx^2##. In my theoretical physics book i read also that the potential is...
26. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 31: Problems and solutions (Part 3)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
27. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 32: Continuous groups in physics (Part 1)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
28. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 33: Continuous groups in physics (Part 2)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
29. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 34: Continuous groups in physics (Part 3)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
30. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 35: Noether's Theorem; Special Relativity (Part 1)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
31. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 36: Special Relativity (Part 2)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
32. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 37: Special Relativity (Part 3)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
33. ### Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 38: Special Relativity (Part 4)

All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
34. I

### Question about tension in 3D

If you have a rectangular box connected on 3 sides with strings, and you hold all the strings together at a point, with your hand; then you put a weight in the center of the box, which is open, would the tension on the strings differ than if you put the weight at a corner. Please describe it to...
35. M

### Dimensional formula of distances in certain formulas

Homework Statement Dimensional formula for 'the square of the distance between two bodies' in universal gravitation and 'distance from the axis squared' in moment of inertia. Is L^2 is the dimensional formula for both the distances in the above two cases? Homework Equations F=Gm1m2/d^2; moment...
36. P

### Can a swing set be too tall?

I plan on building a swing set for my daughter, and I always loved the feel of a good tall swing. I like the long range of motion, the nice glide ... but is there such thing as too tall? I was planning on going about 14' off the ground with the cross beam .. then I figured, well, let's go with...
37. ### I Help with Python modelling of a particle in a 2D box

Hello guys, I programmed a physics simulation where a particle with some initial conditions bounces off the walls of a 2d container. The simulation also includes gravity in the y-coordinates. The aim of the project is to produce a visual animation and further on include more particles and...
38. ### Question about self-study of SR

Hi, I was wondering, as in the Bachelor's degree curriculum there is no SR course, for one who is interested in theoretical physics (as me), would do it alone, perhaps with texts such as Rindler or Synge ...? Thank you in advance !
39. ### Determine the angular momentum in polar coordinates

Hi there, I've been trying to solve the following problem, which I found looks pretty basic, but actually got me really confused about the definition of angular momentum. Problem The trajectory of a point mass m is described by the following equations, in spherical coordinates: r(t) = r_0 +...
40. ### I Is there a contradiction in Halliday and Resnick?

In Chapter 11, section 11-4, subsection friction and rolling, it is stated that the static frictional force is along the same direction as the direction of motion because the point of contact of the wheel with the floor is moving in the opposite direction. Then, in the next subsection, the same...
41. ### Definition of Success problems with projectile motion

So I just got beat up by this question on my midterm. I'm not sure if these problems are always called definition of success but that is how my professor refers to them as. The question: (paraphrased) When you walk into your dorm room you like to throw your keys onto the center of your desk...
42. ### A What is orientation of a needle shaped spacecraft?

this is a small part of a problem on tidal forces and I wasn't sure what the question asks as it seems to me that more information is needed. Am I right or is there something I am missing? the question goes as: "A spacecraft approaches a neutron star of radius 10 km and mass 1.5 times mass...
43. ### Potential energy = infinite?

Hi everyone, first post here. Today i crushed into a question. I was going to write it down here, then i crushed into another one. Lets say we want to know the potential energy of a body relative to a center of gravity. I will refer to gravitys acceleration as "g" and to mass as "m". "k" will...
44. ### What are the aspects that can help a car to flip in a turn?

I am not sure if this is the right place to ask it, but this is a question that I thought today, and it gave me some curiosity to understand. Imagine that a car will curve, we can say the turn is a bit tight , what are the factors that can help it to flip? I was wondering about some aspects...
45. ### Name of Online Journal with Immediate Online Review

Hello everyone. A Philosophy of Science friend showed a site where you can upload your paper and then you will be fairly quickly reviewed by your peers and this will be published alongside your paper. It seems to me this is a very good way to proceed; you may get assessment from the very top...
46. ### B Path of a particle.

Hi There. I want to ask a question, here it is :- How to find the path of a particle if initial velocity(vector) is given and constant force(vector) acts on the particle. Like :- 1) How can we determine the path will be PARABOLIC 2) How can we determine the path will be CIRCULAR. 3) How can we...
47. ### Acceleration of a Rocket falling to Earth

I want to drop a rocket-shaped object from a near-space balloon, with the aim of maintaining a downward acceleration that leaves it's contents in microgravity. I think that this means: The (unpowered) rocket needs to maintain as close to 9.8m/s2 acceleration in order to balance out the...
48. ### Precession and weight

Many of you might have seen veritasium's video on the "Anti-gravity wheel". Through one of the comments, I was introduced to the idea that the reason the apparatus is so easy to lift is because the energy to do so comes from the spin of the wheel, i.e. its rotation slows down as it is lifted and...
49. ### Out of phase EM Wave

Why can't we have an Electromagnetic wave in which the Electric Field and Magentic Field aren't in phase?
50. ### Conservation of Energy vs Conservation of Momentum problem

Homework Statement We are trying to find out whether we can hit a weight ##m=3## kg up to a given ##h=15.24## meters with a hammer with a head of ##m=6## kg swung at ##v=10## m/s. Homework Equations KE=0.5mv^2 PE=mgh p=mv The Attempt at a Solution One solution is to even see if the energy...