What is Motion: Definition and 1000 Discussions

In physics, motion is the phenomenon in which an object changes its position over time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and time. The motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame with change in time. The branch of physics describing the motion of objects without reference to its cause is kinematics; the branch studying forces and their effect on motion is dynamics.
If an object is not changing relatively to a given frame of reference, the object is said to be at rest, motionless, immobile, stationary, or to have a constant or time-invariant position with reference to its surroundings. As there is no absolute frame of reference, absolute motion cannot be determined. Thus, everything in the universe can be considered to be in motion.Motion applies to various physical systems: to objects, bodies, matter particles, matter fields, radiation, radiation fields, radiation particles, curvature, and space-time. One can also speak of motion of images, shapes, and boundaries. So, the term motion, in general, signifies a continuous change in the positions or configuration of a physical system in space. For example, one can talk about the motion of a wave or about the motion of a quantum particle, where the configuration consists of probabilities of occupying specific positions.
The main quantity that measures the motion of a body is momentum. An object's momentum increases with the object's mass and with its velocity. The total momentum of all objects in an isolated system (one not affected by external forces) does not change with time, as described by the law of conservation of momentum. An object's motion, and thus its momentum, cannot change unless a force acts on the body.

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  1. Andrei0408

    Simple and driven harmonic motion

    I know you can't solve it and just give it to me, I just want to know what I'm supposed to do, if you need any more information or clarification please let me know. Thank you for taking the time to help me!
  2. K

    Is Air Resistance Negligible in Projectile Motion Experiments?

    Total acceleration equaled = -9.81
  3. SamRoss

    I How is the weak force related to a change in velocity?

    Hi everyone, The four fundamental forces are gravity (I understand that G.R. does not look upon gravity as a force but I'm not worried about that here), the Lorentz force, the weak force, and the strong force. I'm familiar with the inverse square law for gravitation and the Lorentz force...
  4. W

    Motion equation problem -- Car accelerating with a constant power engine

    So I tried to solve this in two methods, but I keep getting different results, and I don't know why.
  5. Andrei0408

    Equation Demonstration -- Comparing a pendulum's motion to an LC circuit

    I've just learned about simple harmonic motion and I've been given the following examples: The physical pendulum (for small oscillations sin(theta)~theta), with the formula (1st pic), and the LC circuit, with the formula (2nd pic). If possible, I need the demonstration for these 2 formulas...
  6. zstraught

    Simple Harmonic Motion Question

    First I use young's modulus to solve for delta y. I get 5.67x10 -5. I am not sure what to do after this, but this is my attempt. Next I do T = 2delta y sqrt(m/k) (I am not sure if I am supposed to put 2 delta y) Solving for f, i get f = 1/(2delta y sqrt(m/k)) F = kx, mg = kx, m = kx/g...
  7. greg_rack

    Uniformly accelerated motion issue

    I went quite confidently on this one, at least at the beginning... I found the instant velocity on the 3rd second(v1=12.2m/1s) and the one on the 4th(v2=14.4m/1s), and subsequently the acceleration(a=2.2/1m/s*s). Since the acceleration is constant, using the law "v=v0+aΔt", I have found v0 which...
  8. H

    Projectile motion -- throwing an object vertically

    I don't need to know how to solve this but I was just looking for the answer. Can anyone help? A man is standing at a launch site. The rocket doesn't liftoff. Frustrated s/he throws it straight up with a speed of 12.42 m/s. It is caught on the way down at a point 5.0 meters above where it was...
  9. S

    Classical mechanics -- Equations for simulating the motion of a body

    Hello forum, i want to make a samulation of a body. The body will be moved horisontal on y,x axis. I want on my simulation the body to change direction many times(for example i want to go for 10sec right and then left end right...). My question is does i need more than one differential equation...
  10. randomphysicsguy123

    Projectile Motion (not on Earth)

    I know I need to solve for acceleration as I am not on Earth and I am assuming I should create a distance vs. time graph. But overall I am unsure what to do. Please help been stuck on this for a while.
  11. O

    Decceleration problem with 3 stages of motion

    1): a=(V-U)/t a=(40m/s - 0m/s) /5sec = 8m/s2 2): U-V/t > t= V/a t= 0m/s - 40m/s / -3m/s2 = 13.3sec 3): 8m/s2 = 8x8= 64m 64m x 10sec = 640m How do I work out the total distance traveled over the 3 stages with the information if its correct for question 3? and do I have to take into...
  12. T

    Mechanics; grade 12 Projectile motion

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  13. greg_rack

    Percentage increase in resistance to motion

    So, I simply used the percentage increase formula for the resistance force, but what I come up with is a 9.5% increase, as opposed to the 44% it should be... Here's my procedure:
  14. M

    Rational motion combined with 2 springs

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  15. Ghostinthemachine

    Question: can we make wind during motion

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  16. O

    How Do You Calculate Race Car Acceleration and Power Output?

    A new development race car of mass 400 kg accelerates from 20 km/h to 200 km/h over a distance of 120 metres. Frictional and wind resistance forces can be assumed to be 1000N during the acceleration. Determine the following: (i)The average acceleration from 20 km/h to 200 km/h (ii)The time...
  17. G

    Casimir Effect experiment and implications on motion theory

    Quantum mechanics has argued for years that space is not a vacuum. Arguments attempting to brush aside quantum mechanics vacuum theory claiming, it's 'just a quantum mathematical theory' can now put to rest. In this article, laboratory experimentation demonstrates that the Casimir Effect can...
  18. rbh

    Linear motion, motorcyclist braking time

    I tried using equations listed above to get the answer, but I get stuck with a and Vi. What am I doing wrong? The answer is 6.7 seconds.
  19. N

    Analyzing Velocity and Force of a Chain in Motion

    My solution: For the horizontal portion of the chain: let at any instant the length of chain inside the tube is x, and at that instant the chain in the tube is having a velocity v. Then, at any instant: ##F = \frac{\mathrm{d} p}{\mathrm{d} t}## ##p##= mass of the chain in the tube at the...
  20. M

    Equations of relative motion with respect to a rotating reference frame

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  21. Vanilla Gorilla

    I Is there a way to translate a particle's spin into regular motion?

    Is there a way to translate a quantum particle's spin into regular motion in any of the directions?
  22. E

    Pulley and Two Masses -- Newton's Law of Motion

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  23. M

    What is Kepler's Formula and How is it Used in Circular Motion and Gravitation?

    Using Kepler's Formula, I tried to solve for the answer but was told that it's incorrect.
  24. peace

    The motion of a charged particle in a magnetic field

    qvB=mv^2/R R=mv/qB= p/qB ! As you can see, the difference between this relation and the relation in question is in 'c'. Maybe my way is wrong. Maybe I should get help from relativity because the speed of light is involved here. Please help. Thankful
  25. mingyz0403

    Engineering Constrained Motion of 7 Masses and 3 Pulleys

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  26. Like Tony Stark

    Tension and reaction force in circular motion

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  27. M

    Question about Formulae for Motion in a Rotating Reference Frame

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  28. AN630078

    Mechanics: Motion of Two Connected Vehicles

    i. Using Newton's 2nd Law, F = m a consider the motion of the entire system, so the car, caravan and towbar an be thought of as a single object. The tension can ignored as it is an internal force. Braking fore + resistive forces = mass * acceleration Braking force + 200N +150 N=(1000+1500)*(0.5)...
  29. M

    Forces: Pulley and Slope Constraining the Motion of two Masses

  30. AN630078

    Kinematics Motion with Variable Acceleration

    The displacement of the particle is; s= ∫v dt s= ∫4-3t^2 dt s=4t-t^3+c When the particle is at the Origin, t=0; 0=4(0)-(0)^3+c c=0 So this becomes; s=4t-t^3 The particle next passes through the origin when; 4t-t^3=0 Factor out the common term -t; -t(t^2-4)=0 Rewrite t^2-4 as t^2-2^2 and factor...
  31. plomeiko

    Question about gravitational potential energy and angular motion

    hello I would like some help with the first part of this homework. for the moment i have done this: E initial=m*g*h Efinal= 1/2 m*v ^ 2+1/2I*ω ^ 2 Ei=m*g*h+1/2I*ω ^ 2 Ef=1/2*m*v ^ 2 my doubt is with the potential energy since it confuses me when there is or not...
  32. AN630078

    Circular Motion of a Cyclist and a Car going around a bend in the road

    Question 1: So we are given three variables; Mass=90kg Angle to the vertical = 20 degrees Speed = 10 ms^-1 There is not enough information to rearrange the formulas for centripetal force or acceleration in terms of r to find the radius. However, I have a attached a free body diagram of a...
  33. Like Tony Stark

    Difference between curvilinear and rotational motion

    The solution states that there's no rotational motion when ##C## is cut (the motion is curvilinear), so we can take torques with respect to the centre of mass of the plate. But, isn't it rotating? I think of it as a pendulum, which describes a circular motion. What's the difference? Wouldn't the...
  34. rad1um

    Stability of Classical Heisenberg Spins (Equation of Motion)

    Consider the classical Heisenberg model without an external field which is defined by the Hamiltonian: \mathcal{H} = -\sum_{ij} J_{ij} \vec{s_i}\vec{s_j} where J_{ij} > 0 describes the coupling between the spins \vec{s}_i \in \mathbb{R}^3 on some lattice. (Is there a way to use tex...
  35. R

    How to set the Magdeberg hemispheres in motion (propulsion)?

    This is about the famous, classic experiment of Magdeburg hemispheres with the Wikipedia link below: https://en.wikipedia.org/wiki/Magdeburg_hemispheres. "The experiment was designed to demonstrate the vacuum pump invented by Otto von Guericke - but also the tremendous 'strength' of the...
  36. M

    Equation of motion in curved spacetime

    1) We know that for a given Killing vector ##K^\mu## the quantity ##g_{\mu\nu}K^\mu \dot q^\nu## is conserved along the geodesic ##q^k##, ##k\in\{t,r,x,y\}## . Therefore we find, with the three given Killing vectors ##\delta^t_0, \delta^x_0## and ##\delta^y_0## the conserved quantities $$Q^t :=...
  37. aspodkfpo

    Energy loss in simple harmonic motion causes the time period to shorten?

    https://www.asi.edu.au/wp-content/uploads/2016/10/ASOEsolns2012.pdf Q11 D) Markers comments: Few students reached part (d) and very few of those who did realized that the amplitude does affect the time taken for each of Mordred’s bounces. i.e. the energy losses results in shorter periods...
  38. Lars1408

    B Time Dilation: Direction of Motion's Effect

    Earth moves through space in a certain direction at a certain speed. Moving faster slows down your clock while moving slower increases your clock. Does this mean that the direction your moving in has an effect on time dilation? In other words, if you move along with the earth’s initial speed...
  39. Hamiltonian

    Classical Which Books Cover Simple Harmonic Motion for High School and Undergrad Levels?

    sites or books for SHM high school and undergrad level. i want to understand SHM from the ground up and I am finding difficulty with my current sources
  40. B

    Spring-mass system in circular motion has a maximum angular speed?

    and this is my solution for question (d), it may seems that $$R=(k)/(k-m\omega^2)R_0$$ so that $$\omega ≠ \omega_i =√(k/m)$$ but $$\omega_c <\sqrt{k/m}$$ is always true, ##\omega_i## corresponds to the limit case when ##F_max## is infinitely large Besides, I don't know other Physics prevents...
  41. Nexus99

    Understanding Motion and Collision in the Absence of Gravity

    These are the solution, I'm not understanding something: In the absence of gravity, the total kinetic energy and vertical momentum are conserved). So we have ## \frac{1}{2} m v_0 = \frac{1}{2} M \dot{Y}^2 + \frac{1}{2} m \dot{y}^2 ## ## 0 = m \dot{y} + M \dot{y} ## Ok. But, if the ball goes...
  42. M

    Simple harmonic motion homework

    I don't know how to start doing this homework. I would like help to orient myself.
  43. B

    Confusion About Rotational Motion

    I watched a video that showed how to calculate the center of gravity of a horizontal bar suspended from two wires, one attached to each end. Each wire was then attached to a vertical wall. The angle each wire made with the wall it was attached to was given. They treated it as an a example of...
  44. M

    Motion when 2D forces are exerted on masses at each end of a baton?

    Let's say you have a simple structure with two equal masses connected by a massless rigid baton of length L. Like this: Imagine this structure is totally free in space. It is not hinged in any way. Then forces act on each mass in 2D (x,y). If you have the x and y force vectors acting on each...
  45. jk22

    Newton's laws of motion in 3+1 dimensions ?

    If it were supposed that time were a 4th non-spatial dimension how would it influence the gravitational movement ? The problem I have when trying to solve this invented problem is that Newtonian physics works in coordinates and that there are a lot of ways to find 4d 3+1 hyperbolic-spherical...
  46. BayMax

    Double pendulum equations of motion using Newton's laws

    I need help to understand this problem taken from Mechanical Vibrations by S. Rao I know that the equations of motion could be obtained in various ways, for example using the Lagrangian, but, at the moment, I am interested in understanding the method he used. In particular, if I'm not...
  47. tanaygupta2000

    Finding the Line of Motion of Two Particles

    I know that I need to find the equation of the line of motion of the two particles, the dot product of which with one of the options will give 0. I began with founding the coordinates of center of mass: R = (m1r1+m2r2)/(m1+m2) = (2a/3, 0, a/3) and velocity of the center of mass: V =...
  48. jk22

    I Why Geodetic Equation Doesn't Accept Schwarzschild Solutions

    In the Schwarzschild metric case why is : $$r=cste,$$ $$\theta(t)=\arccos(\sin\alpha\cos\omega t)),$$ $$\phi(t)=\arctan(\tan(\omega t)/\cos\alpha),$$ $$t=\tau$$ not solution to the geodetic equation ?
  49. G

    Mechanics Circular Motion Question

    Part (i) *Pink represents mark scheme method Part 2 However I am still confused on the diagram.
  50. LCSphysicist

    Why did my analysis of critically damped motion lead to the wrong solution?

    Why is my analysis of critically damped motion wrong? x'' + y*x' + wo²x = 0 Choosing a complex number z as z = A*e^i(wt+a) and putting on the equation calling x as the real part of Z w = ( i*y +- (4wo²-y²)^(1/2) )/2 (bhaskara) 2wo = y (critical) w = iy/2 z = A*e^i(ity/2 + a) z = A*e^(-yt/2...
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