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. emarie

    Calculate the magnitude of the velocity at point from a given equation, a(t)

    These questions keep appearing in my past-papers and yet at no point in the course notes can I find a worked solution. Unfortunately I'm not sure where to start. My initial thoughts were regarding getting an equation using known values but w.r.t. to t and integrating for v, but like I said I...
  2. W

    A The problem of the mass of a body

    if we have known the density functionρ(r),and then we can calculate the total mass of a spherical body. M=integral of ρ. Now we will say that body has mass M, but I think it is wrong. according to special relativity, mass is equal to energy, so we can also say that body has total energy M,but i...
  3. Susie

    Tension Force Problem: Solving for T1 with x and y components using trigonometry

    I know I have to find the x and y components of T1 using 400cos(55) and 400sin(55) and I know that the x-component of T1 will = the x-component of T2 but opposite sign to give 0. But idk how to get there and what do to for the y-component. I think I found the weight, I think it’s 32.42g but I’m...
  4. J

    Focal length of converging thin lens graphs

    I tried -M=pq = f/(f-p) = f/f - f/p = 1-(f/p) => M+1= -f/p => -Mp-p=f But since it’s the y intercept, p will equal zero and so the focal length will be 0?
  5. nineteen

    Why is Kinetic Energy a scalar quantity?

    Why is Kinetic energy a scalar quantity? I read in an article, it said, when the velocity is squared, it is not a vector quantity anymore. Can someone fill in the gaps for me? I can't quite get what that article said. And I would be pleased if you provide some other examples other than kinetic...
  6. matai

    Using Integrals to Calculate the Rotational Energy of Earth

    So I found the linear velocity by using the circumference of the Earth which I found to be 2pi(637800= 40014155.89meters. Then the time of one full rotation was 1436.97 minutes, which I then converted to 86164.2 seconds. giving me the linear velocity to be 465.0905584 meters/second. I know that...
  7. D

    Time of closest approach between two particles

    Homework Statement Two objects ##1## and ##2## move at constant speeds ##v_1## and ##v_2## along of two mutually perpendicular lines. At the moment ##t = 0## the particles are located at distances ##l_1## and ##l_2## from the point of intersection of the lines. At what time will the two objects...
  8. M

    Find the area and length of a gold leaf

    Homework Statement Gold, which has a density of 19.32 g/cm3, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 3.872 g, is pressed into a leaf of 5.372 μm thickness, what is the area of the leaf? (b) If...
  9. M

    Repulsion of the Earth's Magnetic Field

    I have a question why a magnet's magnetic field or a coil's magnetic field will not oppose the Earth's magnetic field? Is it because the Earth's field is not strong enough or the magnet/coil doesn't cover enough square area? What formula's would I use to figure out what strength or area I...
  10. SebastianRM

    I What is the gravitational component in the radial direction?

    Hey guys, I reading over Taylor's Classical Mechanics book. Chapter 9, Centrifugal Acceleration Section. In p.346 he mentions that for a free fall acceleration: g = g_0 + Ω^2 * Rsinθ ρ Where its radial component would be...
  11. Penguin98

    The thickness of glass and the longest wavelength

    Homework Statement In your research lab, a very thin, flat piece of glass with refractive index 2.00 and uniform thickness covers the opening of a chamber that holds a gas sample. The refractive indexes of the gases on either side of the glass are very close to unity. To determine the thickness...
  12. tworitdash

    Classical Which classic book to follow for Advanced EM?

    The book should have the following content. I want to refer a classic book which explains every detail. 1) Ohmic losses at high frequencies 2) Potentials and Green's functions 3) Image theorem 4) Fields radiated by sources in the far field region 5) Equivalence and reciprocity theorems 6)...
  13. SebastianRM

    I Understanding the Hermitian Conjugate in Inner Products

    Hey, I am currently reading over the linear algebra section of the "introduction to quantum mechanics" by Griffiths, in the Inner product he notes: "The inner product of two vector can be written very neatly in terms of their components: <a|B>=a1* B1 + a2* B ... " He also took upon the...
  14. SebastianRM

    What happens to the Electrical Potential the closer we are to a point charge?

    So I have been wondering: The potential for a point charge at the origin, is described as: (Using the reference point at infinity): V=1/(4πε) * q/r My question is, what happens to this Potential the closer we are to the point charge, and so the closer we would get, the Potential seems to go...
  15. M

    Delay and Sum Beamforming Equation Derivation

    Homework Statement I have to simplify this beam form (equation 1) which simplifies to equation 2 and then finally to equation 3. Homework Equations equation 1: e^-ix((1-e^y)/(1-e^z)) where x = Beta*M_(1/2), y = beta*M, z= Beta equation 2: sin(M*Beta/2)/(sin(Beta/2)) equation 3...
  16. I

    I Calculating the Mass of a Piston for a Spring-Based Launcher

    I am trying to teach myself Physics, so I can use it in engineering for my own devices. The project I am working on right now is a very simple spring based launcher. This is frustrating me to no end. Here is my objective. I want to lunch a golf ball about 10 or so feet. I know that I need to...
  17. devilish_wit

    I'm stuck This is a combination of dynamics and free fall

    Homework Statement A flat cushion of mass m is released from rest at the corner of the roof of a building, at height h. A wind blowing along the side of the building exerts a constant horizontal force of magnitude F on the cushion as it drops as shown in the figure below. The air exerts no...
  18. T

    Find v(t) from Newton's Second Law and Differential Equation

    <Moderator's note: Moved from a technical forum and thus no template.> Is what I have done correct ? I want to find v(t) from Sigma F = m*a. I have gravity force mg pointing downward with positive direction and resistive force R = -b*v^2 pointing upwards with negative direction are acting on a...
  19. D

    What is water impact velocity formula?

    Hello Everyone, I am brand new to this forum and I am currently doing "student research project task" where I need to conduct my own experiment basically. I am currently struggling to find a formula for an impact velocity. I hope there is someone in this forums that could help me. What I...
  20. AgusCF

    I Solving Planar Fluence: Ratio of Electrons per cm2

    Hello everyone, Suppose a situation where you have a broad plane-parallele beem of electrons which is perpendiculary incident upon a thin foil which scatters the e- for an angle X. I did calculus and the ratio of flux density below the foil respect with the foil remove is 1.06. But, What are...
  21. Arjun Singh

    KiloNewton/Pound foot of thrust into Horsepower units

    Hi, I am currently studying aviation engine outputs and to make my study linear in comparative analysis with standard Automotive engines I need some expert help. Can anyone help me drive precise equations to convert: 1. Engine thrust in Kilo Newton into Horse Power and Watts 2. Engine thrust in...
  22. A

    I Verifying Equality: \mathcal{Im}[A+B+Te^{2ip}]=0

    I have an expression ##\mathcal{Im}[RT^*e^{-2ip}]=|T|^2\sin p ##, where ##R=Ae^{ip}+Be^{-ip} ## and ##p ## is a real number. This ultimately should lead to ##\mathcal{Im}[A+B+Te^{2ip}]=0 ## upto a sign (perhaps if I didn't do a mistake). There is a condition on ##R ## that it is real...
  23. Lyakhnitskiy Dmitriy

    B Energy of a Wave: Amplitude vs Frequency

    I need help with this question. The energy of wave related to its amplitude but not to frequency. If we talk about wave as disturbance carring energy we can imagine a swinging rope that gives potential energy to body by pushing it up. Bigger amplitude means getting high and increasing Potential...
  24. L

    Center of Mass Balancing Question

    The question is: The orange and blue cat are currently balanced on the see saw. The orange cat then eats a bird, which of the following could make the see saw balanced again? - I attached the picture that the question is referencing. And the possible answers are: A. Orange cat stays at same...
  25. K

    Intro Physics Difference Between 3rd and 10th Editions of Halliday/Resnick?

    Hi, So I'm trying to self-study AP Physics C and found the first volume of Halliday/Resnick's Fundamentals of Physics on my parent's shelf, 3rd edition (from 1988). They also have the 2nd edition of University Physics, volume 2 (E&M). I do, however, have a copy online of the extended 10th...
  26. Ushitha Dissanayake

    How to find the coefficient of kinetic friction

    Homework Statement The speed of a 4.0-N hockey puck, sliding across a level ice surface, decreases at the rate of 0.61 m/s2. The coefficient of kinetic friction between the puck and ice is: A) 0.062 B) 0.25 C) 0.41 D) 0.62 E) 1.2 Homework Equations I'm not too sure but i know that : If the...
  27. R

    Calculus derivatives word problem

    Homework Statement Is it possible to accurately approximate the speed of a passing car while standing in the protected front hall of the school? Task: Determine how fast cars are passing the front of the school. You may only go outside to measure the distance from where you are standing to the...
  28. E

    Finding the change in weight from the force & difference in height (y)

    Information Given:In 1956, Frank Lloyd Wright proposed the construction of a mile-high building in Chicago. Suppose the building had been constructed. Question: Ignoring Earth's rotation, find the change in your weight if you were to ride an elevator from the street level, where you weigh 708...
  29. C

    Arbitrary Circulation Calculation with Fourier Series

    Homework Statement Homework Equations The Attempt at a Solution I am stuck trying to figure out why there are three different alphas and why in the equation we are supposed to use has a theta and what that means. If I can set up the Fourier series I can properley I know how to solve it for...
  30. O

    A Capacitor with initial charge

    Homework Statement A capacitor with initial charge q0 is discharged through a resistor. What multiple of the time constant τ gives the time the capacitor takes to lose (a) the first 1/8-th of its charge (b) 7/8-th of its charge? Homework EquationsThe Attempt at a Solution since ı know...
  31. Manolisjam

    Non-conductve sphere with cavity -- find Electric field

    I have a non conducting sphere with a charge ρ=A/r per uni vollume A is constant. suppose there is a cavity in the centre and within a particle of charge q. i want to find the E inside the sphere in respect with r. Homework EquationsThe Attempt at a Solution for radius equal of the cavity i get...
  32. S

    Looking for tricky and interesting physics and maths questions

    I want to do tricky physics and maths questions that require only A-level knowledge of maths and physics to solve. Questions that don't have a straightforward answer and will help me to develop my logic and problem-solving skills. I'm looking books, online resources and etc.
  33. D

    What Does the 10% Resistance Boundary Mean in Circuit Measurements?

    Homework Statement if someone could help me with this it would be much appreciated. In physics, I used a 98Ω resistor in a series circuit and measured the current and voltage output from battery, using the current and voltage I calculated the resistance. I=0.0094A V=1 Rt=1/0.0094=106.38Ω even...
  34. A

    What are the values of Rf and V2 for the given circuit?

    Homework Statement Hello, I am trying to Calculate The Resistance Rf and the value of the Voltage V2. The setup is a logarithmic Op amp connected to a differential Op amp. Both Op amps obey the Golden Rules. Attached below is my attempt at the solution and the question. Currently, I have an...
  35. S

    Momentum and bar chart representations

    One day Steve (68 kg) rolls into class on a skateboard. When he rolls in on the skateboard, he and the skateboard move at 2 m/s toward the windows in the room. Steve then jumps off the skateboard and he ends up moving at 1.0 m/s toward the windows of room. How fast and in what direction is the 1...
  36. Jay Macarus

    I Calculate the distance between two cleaved crystals

    Hey guys, can't seem to make sense of this question from phys. It goes.. "A crystalline solid consists of atoms stacked up in a repeating lattice structure. Consider a crystal as shown in Figure a. The atoms reside at the corners of cubes of side L = 0.200 nm. One piece of evidence for the...
  37. F

    Commutation Relation: Hi Parity Operator?

    hi, do the translation operator commute with parity operator?
  38. K

    Ultrasound waves and the kidney

    Homework Statement In a kidney study, ultrasound was used with frequency 3.5 MHz. In normal body tissue, the speed of the ultrasound is 1.50 km / s, while the speed in the kidney tissue is 1.55 km / s. Reflected signals came as follows: after 20 microseconds from the skin, after 75 microseconds...
  39. M

    I Exploring Emergence: Examples, Theory, and Experiments for a School Project

    For a school project, I've got to choose a subject. I chose "Emergence", but I have to narrow it down a little bit. So, that's why I'm creating this topic. The definition of emergence that I use: By emergence, I mean the fact that proprieties of one scale implies other proprieties by changing...
  40. Hi Im Paul

    Python What's wrong with my bisection method code?

    Hello, I am assigned to write a code using bisection method (aka binary search method) The equation is 10sin(x) - x^3 - N where N = 1,2,3,4,5,6,7 My code is from math import sin def neg(a, b): return a*b> 0 def bisectx(funcx, lowx, highx,n): assert not neg(funcx(lowx,n), funcx(highx,n))...
  41. KAM123

    Calculating Initial & Final Enthalpy, Kinetic Energy & Power in a Turbine

    A turbine operates under steady-flow conditions. It receives steam at a pressure of 15 bar, specific volume of 0.1318 m³/kg, velocity of 30 m/s and specific internal energy of 2594.5 kJ/kg. The steam leaves the turbine at a pressure of 30 kPa, velocity of 90 m/s, specific volume of 4.25 m³/kg...
  42. J

    What is the Ideal Gas Law for a Two-Bulb System with Varying Temperatures?

    1. Two equal glass bulbs are connected by a narrow tube and the whole is initially filled with a gas at a temperature of T0 and pressure of P0. Then, one of the bulbs is immersed in a bath at a temperature, T1 and the other in a bath at a different temperature, T2. Show that in this problem, the...
  43. S

    Computer engineering projects for physics. Proposals?

    i'm a computer engineering student but i have always been interested in physics and wanted to contribute to it,next semester i will be working on my senior project and i was wondering if any of the physicists here or scientists in general think that there's something that i could create whether...
  44. chrononaut 114

    "From your data, is the bandgap of ZnSe direct or indirect?"

    (urgent) Hi, This question was apart of an assignment sheet that I was given in 'Experimental Physics III' after having completed and obtained data for the practical called 'The Bandgap Energy of Semiconductor ZnSe'. Cheers Below is some screenshots of the (Matlab-processed) data we obtained...
  45. mkematt96

    Engineering Help finding error in my Circuit Analysis

    Homework Statement Homework EquationsThe Attempt at a Solution My values for i1,i2,and i3 were: -.005179,-.002857 and .004857. When I ran the same circuit through LT Spice the values they gave me were .00059081,.000809628, and .00119037. Where did I make my error? * as a side not I...
  46. EastWindBreaks

    Why is the height of point 2 same as point 3?

    Homework Statement Homework Equations The Attempt at a Solution Is it an assumption because the difference in height is small?
  47. EastWindBreaks

    Why is the second approach incorrect? pulley problem

    Homework Statement Homework Equations friction force = F_v m=m1 The Attempt at a Solution is method 1 correct? if so, why method 2 came out with a totally incorrect answer. I understand that you can also set up acceleration equations for m1 and m2, since their acceleration are equal, and...
  48. G

    What Questions Do New Physics Learners Have?

    I've just started learning Physics and I'm going to have so many question from now on. Thank you in advance for helping me :wink::oops:
  49. R

    Completely stumped on this one -- Kinematic Conceptual problem

    Homework Statement You are at a stoplight when you see a car approaching from behind at constant velocity. To avoid getting rear-ended, you accelerate forward with constant acceleration. Assume that you have managed to start at the last possible instant to avoid getting hit, as determined by...
  50. R

    I Vector Triple Product - Physcial Significance

    Hii, As we know, Scaler triple product is volume of parallelopiped constructed by its three sides. Similary, What is the physical significance and geometrical interpretation of Vector triple product ? Also, What are the application where we use such mathematics and why ? Regards, Rahul
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