What is Physcis: Definition and 208 Discussions

Physics (from Ancient Greek: φυσική (ἐπιστήμη), romanized: physikḗ (epistḗmē), lit. 'knowledge of nature', from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy.
Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

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  1. S

    I Stopping forces in an emergency stop

    Hi I'm trying to calculate the forces applied when suddenly stopping an object. I have a pair of winches which lowering an object at 400mm/s and would normally decelerate to a stop at 150mm/s^2. If the Estop for this winch is hit then we decelerate at 2000mm/s^2. However, if the power is...
  2. S

    Ideal conditions in which circuit analysis is done

    What are the ideal conditions in which circuit analysis or analysis of an electrical system is done?I know that the air friction,friction between materials is ignored in ideal systems, such as for ohms law applications.What else is ignored in analysis of ideal electrical systems?
  3. K

    Block sliding up an inclined plane

    1. The problem statement, all variables, and given/known data A block with an initial speed of 20.0m/s slides up a ramp with an incline angle of 30º. (a) (2 points) Write the position as a function of time for motion up the surface of the ramp. (b) (2 points) Write the velocity as a function...
  4. D

    I Einstein's light clock thought experiment

    I'm an engineer who has an amateur interest in physics. I have been reading about Einsteins light clock experiment. I understand the principal that when a light clock on a train etc is moving relative to a standing still observer then the light must travel a longer distance per tick. given that...
  5. Y

    Studying Can I Pursue a Career in Physics with Weak Math Skills and Specific Interests?

    Hi, I am really very interested in learning physics and becoming researcher or scientist. But I have few problems like I am not good at maths at all I can remember formulas and constants value. I am not at all interested in electricity and magnetism. I don't really know what am I good at. I...
  6. M

    Find the centre of mass for this sheet of paper with a cutout

    Homework Statement A uniform, rectangular sheet with sides of lengths a and b has a hole of dimensions a/4 by b/4 punched in it as shown below. Find the centre of mass of the sheet after the hole is made. Homework Equations CM= ∫xdm/∫dm The Attempt at a Solution I'm confused on what to...
  7. M

    Acceleration change during teleportation

    Let's assume that it is possible to teleport safely (in one piece, with same body structure) to different galaxy using something as wormhole. Then what would be acceleration that participating in such travel human experience? As I know solar system travels at 230 km/s around the galactic...
  8. F

    Find electric Field at a point A

    Hi Guys, I've been learning electric field, and i want to ask about this question.EF net = EF1 + EF2 my EF1 = 9 x 109 * 4 x 10-8 / (0.6)2 = 1 x 103 (From Q1) EF2 = 9 x 109 * 2 x 10-8 / (0.3)2 = 2 x 103 (From Q2) then EFnet = (2+1) x 103 = 3 x 103 and what i get from key answer is 2.2 x 103...
  9. P

    Carnot Cycle: Analysis of Energy Exchange

    A refrigerator operates on a Carnot cycle. In this cycles, it absorbs 120 J of energy at a temperature Tc while 300 J of work is done on the gas undergoing the cycle. How much energy is exhausted as heat during this process? The answer is 420 J. I am unsure of where to start for this...
  10. Ahmad Esber

    What Curious Questions Do You Have About Physics?

    Hello astronomers and physicists! My name is Ahmad. I'm Lebanese studying in Dubai, majoring in aeronautical engineering. I'm usually very curious about everything concerning physics, and not only aeronautics. So expect questions concerning various areas of physics. I'm also sometimes Mr...
  11. K

    Static Electricity powered toy car project for school

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  12. J

    Estimating Electromagnetic Radiation from a Cellular Phone

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  13. A

    Schools Interested in learning physics after graduating college

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  14. S

    Thomas Young's Double-Slit Experiment Problems

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  15. P

    Other Doing a physics Masters after a CSE Bachelors

    Hi, european here. To some circumstances I can't study physics anymore but I'd like to still get into physics. So currently I'm studying computational science at ETH Zürich. Although we can focus in theoretical physics in our bachelors "thesis", the curriulum differs a lot when compared to...
  16. A

    B Zeno's arrow paradox and general relativity?

    I don't know much about general relativity, but I'm curious if Zeno somehow foresaw the reallty of the universe many many years before Einstein did(without any rigour ofc, but still the idea holds?). Understanding the Zeno's arrow paradox, stating that an arrow is motionless at a certain moment...
  17. A

    Confusion about the magnetic field

    I'm having some confusion about the creation of magnetic field lines. How I understand it so far, is that a magnetic field is basically an electric field viewed from a relative point. I don't have a great understanding so far, as I just started to learn about it, but I've learned that objects...
  18. A

    Classical Companion book for Electrodynamics by Jackson

    I am studying electrodynamics, in a few more months I have the qualification exam. The guide text is classical electrodynamics, Jackson. I find that book is higher my current level. I have the math tools, but what book do you recommend to use before the Jackson.
  19. E

    Moment of inertia for this assembly

    Homework Statement A slender rod is 80.0 cm long and has mass 0.120 kg. A small 0.0200-kg sphere is welded to one end of the rod, and a small 0.0500-kg sphere is welded to the other end. The rod, pivoting about a stationary, frictionless axis at its center, is held horizontal and released from...
  20. L

    Voltage across two different circuits

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  21. H

    Single slit with minimum uncertainty

    Homework Statement A horizontal beam of laser light of wavelength 474 nm passes through a narrow slit that has width 5.80×10−2 mm . The intensity of the light is measured on a vertical screen that is 2.40 m from the slit. Use the result of part A to estimate the width of the central diffraction...
  22. D

    Programs What Are Current Issues Whose Answers Lie in Physics?

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  23. Shaun Harlow

    A What is the formula 1/(dS/dE)>>0 and how does it apply?

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  24. counlin

    Courses Change of plans: from CS to Physics?

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  25. M

    Understanding Sinusoidal Waves: Exploring Phase, Wavelength, and Amplitude

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  26. Ian Baughman

    Electron in orbit of around a single proton

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  27. N

    Calculating Internal Energy & Temperature Change of Ideal Gas

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  28. H

    Many Body bogoliubov transformation

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  29. Cjosh

    Taking physics and dealing with depression/anxiety

    I suffer from serious bouts of depression/anxiety that come and go for no obvious reason. I started physics this year and its hit me half way through the semester. I made a doc appointment to fix this and I am afraid it will hurt me academically if its not fixed and I won't be able to do awesome...
  30. P

    Very quick easy Trig/Angle question

    Homework Statement The river flows 5km/hr in the west direction. The boat that has a speed of 10km/hr. It starts from the south bank to the north. Then the question is to essentially find the angle theta. Homework Equations Tan-1(5/10) or Tan-1(10/5)The Attempt at a Solution Tan^-1(5/10) or...
  31. MiLara

    I Why do some but not all derivatives have physical meaning?

    I know that taking the derivative of certain functions that explain physical phenomena can lead to another statement describing the physical system, the most famous being the derivatives of position. That is, position-->velocity-->acceleration-->jerk-->jounce...and taking any other further...
  32. joshua cruwys

    Examine the following circuit and complete the table

    so for resistance I've gotten r1=6 r2=5 r3=8 and r4=12. then for current i got r1-.30 r2=.24 r3=.06 r4=.06 amd volatge r1=1.8 r2=1.2 r3=.48 r4=.72. I am not sure about my voltage for r3 what i did was Vt-r1-r4 and when i add them up i get 3v so that should be right? and I am also not sure about...
  33. thecourtholio

    Interaction Energy For Two Point Charges

    Homework Statement Find the interaction energy ( ##\epsilon_0 \int \vec{E_1}\cdot\vec{E_2}d\tau##) for two point charges, ##q_1## and ##q_2##, a distance ##a## apart. [Hint: put ##q_1## at the origin and ##q_2## on the z axis; use spherical coordinates, and do the ##r## integral first.]Homework...
  34. Awais gul

    Why Does a Ball Bounce Back from a Wall But Not from Sand?

    Hello, I am Awais gul, a student of science subjects and learning the basic of Physics , chemistry and computer science.I have a Question about Newton's third law of Motion. Question : If we Throw a ball on a wall it goes back but if we throw a ball on sand why it does not go back? Newton's...
  35. Oganesson

    Programs I have a degree in Medicine and want to study Biophysics?

    Is it necessary to have a Physics or Biology degree in order to pursue a Masters in Biophysics ?
  36. Aaron M

    Physics How much weight does working/school full time carry

    I am 29 with a wife and daughter, scheduled to graduate in 1 year with a B.S in physics. My GPA currently sits at a lowly 2.5, however I have been working full time(40 -52 hours a week) while being a full time student. I mostly have received B's in my core classes (2.79 GPA in major). Do...
  37. S

    I Bicycle Forks: The Role of Curvature in Stability and Steering

    I see that modern bicycles have curved front wheel forks , how does that affect stability ?
  38. T

    Physics of Solids: Elastic Limit & Fracture Stress

    For brittle substances can we say that elastic limit is equal to fracture stress ?
  39. Oganesson

    I Is Jupiter too big to orbit the Sun?

    I read the Jupiter is so big that it doesn't really orbit the sun. Is that true?
  40. O

    I would like to know what the dynamic force load is....

    Homework Statement I am currently doing an internship and as part of my assignemnt I have to calculate the dynamic load on the bearing of a certain part that is rotating about a fixed point. https://www.physicsforums.com/attachments/chute-png.103400/ This is the part that moves ( the brown...
  41. Ian Baughman

    Physics Reading For Undergrads

    So I am transferring from a community college to the university after this coming semester for a physics degree. Being a transfer student I am expecting to be at a disadvantage when compared to the other students at the school. I have had Calculus based physics 1 and 2 which mainly is focused...
  42. S

    What is the optimum wing angle and corresponding travelled?

    The forces acting on the glider are the gravitational force, the lift force and the drag (air friction). The drag () and lift force () are a function of the angle that the wings have with the gliding direction. =122 with: =0.1+3∙10−32 =122 with: =0.2+0.1− 3∙10−32 In the above equations, is in...
  43. S

    What are the Top Topics in Physics for a 16-Year-Old Physics Lover?

    Hi everyone. My name is Shawn and I'm 16 years old. I'll be beginning 12th grade in June. I am a very very big physics lover and I simply adore math. In physics, I am particularly interested in general relativity, quantum mechanics and most of all, superstring theory. I hope to improve my...
  44. D

    The value of electric current on a sinking conductor

    Homework Statement A flat capacitor formed by two square plates of side 0.3 m which are 2 mm apart. Source keeps voltage 250 V on the plates. What current flows between the plates and the source if the condenser is immersing in kerosene at velocity of 5 mm / s? The relative permittivity of...
  45. ThePizzaDeliveryGuy

    Average Passenger Plane Terminal velocity with added speed

    A passenger plane is traveling at a speed of 500 knots, has a mass of 72574.7792 kg, and has an altitude of 35,000 feet. If the pilot lost control of the plane and couldn't reduce speed or anything and the plane was going down at approximately a 40 degree angle, how long would you have until it...
  46. S

    Young's double slit experiment help

    1. The statement, all variables and given/known data Hi I'm doing this experiment where we need to find the wavelength of our laser light source. I am unsure what the variables IV and DV would be and the controlled variables? Also how will I make the graph? I'm in AS level so please don't make...
  47. C

    Finding tension in a string from a suspended object

    Homework Statement A 0.02 m x 0.01 x 0.03 block of copper (density = 8.8 g/cm3) is suspended submerged in milk (density = 1.03 g.cm3) by a string. How much tension is in the string? Homework EquationsThe Attempt at a Solution My initial thought for an equation was: T+Fb(buoyancy)-mg=0 T+...
  48. I

    Dynamics and Kinematics Interview Question Examples

    So, my teacher is going to do almost like an interview to the class, asking our knowledge about Dynamics and Kinematics, and I was wondering if I can get questions to test my knowledge in Dynamics and Kinematics to get ready for it.
  49. sara lopez

    Thermodynamics: air expansion in a cylinder

    Homework Statement Consider air expansion inside a cylinder. Assume that the volume and initial pressure is 1 ft^3 and 1500 PSI ABS respectively. If the expansion process is reversible and the path is given by P.V^1.4=constant. Calculate the total work done by the gas to reach the final volume...
  50. T

    Difference between density and unit weight with same units

    In my lectures and notes my professor keeps writing out density as lbs/ft3 and unit weight as lbs/ft3. For a material such as concrete it could have a density of 167 lbs/ft3 but a unit weight of 103 lbs/ft3. I am confused as to how these two values are different even though they have the exact...
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