What is Laws of motion: Definition and 214 Discussions

In physics, a number of noted theories of the motion of objects have developed. Among the best known are:

Classical mechanics
Newton's laws of motion
Euler's laws of motion
Cauchy's equations of motion
Kepler's laws of planetary motion
General relativity
Special relativity
Quantum mechanics

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  1. paulimerci

    Newton's Laws of motion -- Bicyclist pedaling up a slope

    F parallel - F applied - rolling resistance = ma I don't know how to calculate for rolling resistance. If the bicycle is not slipping rather it is rolling, should I ignore rolling resistance? And if I ignore that I would get, F parallel - F applied = ma F applied = F parallel -ma...
  2. paulimerci

    Newton's Laws of motion

    How to find frictional force when coefficient of friction is not given?
  3. M

    B Irreversibility of Aristotle's law

    "Reversibility means that we never lose information, that at a fundamental level we can always retrodict the past as well as predict the future in the laws of physics". Susskind in his Theoretical minimum Lecture 2 describes about the laws which are true and which are not. He tells the law of...
  4. sachin

    Choosing what consists of a "system" in Newton's laws of motion

    The question is solved in a single step by taking the blocks as a system and using conservation of linear momentum in the horizontal direction as there is no net force acting in the horizontal direction. Conserving the momentum we get, m x v + M x 0 = (m+M)v', so,,v' = mv/(m +M).where v' is the...
  5. SpectraPhy09

    Plotting the graph of Friction Force vs. time (Laws of motion)

    F.B.D Of first block (I have shown only the horizontal Forces) f1(max) = μ (1kg)(g) = 0.5 * 10 = 5N F.B.D Of the second Block f2(max) = μ (3kg)(g) = 15N Now the string will become taut and the tension will start acting when f = t = 5N But for 0<f<5N there will be no motion between the 1 kg...
  6. H

    Forces and laws of motion -- Big gorilla hanging from two vines

    About 50 years ago, the San Diego Zoo, in California, had the largest gorilla on Earth: its mass was about 3.10 × 102 kg. Suppose a gorilla with this mass hangs from two vines, each of which makes an angle of 30.0° with the vertical. Draw a free-body diagram showing the various forces, and find...
  7. kara123

    Newton's laws of motion -- Force of gravity on a skydiver

    I think you would do force of gravity= mass x acceleration acceleration of gravity= 9.8 m/s mass 75 kg 75kg x 9.8 m/s =735 N i don't know if that's right but i have no idea how to calculate it after he lands, any help would be greatly appreciated!
  8. M

    I Configuring Laws of Motion: Static/Dynamic

    $$\Box A_\alpha +\mu^2 A_\alpha = 2\beta A_\mu \partial_\alpha A^\mu + \frac {4\pi}{c} J_\alpha$$ where ##A=(\Phi, \vec A)## and ##J=(\rho, \vec J)## using a static configuration first where ##α=0## and then a dynamic one where ##α=i## knowing that ##E= - \nabla^2 \Phi - \frac {\partial...
  9. M

    I Laws of Motion for New Lagrangian: Partial Differential Equations

    $$\partial^\beta F_{\beta\alpha} +\partial^\beta A_\mu A^\mu \delta^\alpha_\sigma \delta^\rho_\beta+\mu^2 A_\alpha = 2A_\mu (\partial_\rho A^\rho) +\frac {4\pi}{c}J_\alpha$$
  10. M

    I Solving Proca Lagrangian w/ Extra Operator: Find Laws of Motion

    The euler lagrange equation I am using is: $$\frac {\partial^\beta \partial L}{\partial(\partial^\beta A^\alpha) }= \frac {\partial L} {\partial A^\alpha}$$ Now the proca lagrangian i am using is $$L= -\frac {1}{16\pi} F_{\alpha\beta} F^{\alpha\beta} + \frac {\mu^2} {8\pi} A_\alpha A^\alpha -...
  11. O

    Equation of motion of a marble moving on a generic vertical guide

    Hello to everyone :smile: I'd like to study this problem. You have a 2D guide, described by an equation y = y (x) in a reference interval x ∈ I = [a, b], placed in a cartesian vertical plane Oxy. The guide is frictionless and the only force that is acting is the gravity force. On this track, a...
  12. 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...
  13. 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...
  14. Prabs3257

    Velocity of an object on an inclined plane

    I used work energy theorem between initial top point and point x along the incline(downwards) i got the expression of v then diffrentiated it to get a maxima but it gives me a wrong ans which is 10/6 but the actual ans is 10/3 please tell me what i did wrong
  15. Prabs3257

    Why is my answer for the rotating wedge problem not matching?

    I tried making the fbd of both blocks the block on the incline will have mgsin30 friction force, tension and centrepetal force's cos component similarly second block will have mg tension and friction where normal will be centrepetal force after solving my ans is not matching
  16. Prabs3257

    Laws of motion and a projectile thrown from an accelerating elevator car

    At the moment of throwing the ball the ball will have a vertical vel of 4 and horizontal of 3 wrt to elevator so as seen from inside the elevator the ball will behave like a projectile where g(eff) = 8 and with time period 1 sec hence range will be the displacement which should be 3 m but ans...
  17. Shivang kohlii

    Constraint relation in a pulley spring system

    Homework Statement How to apply constraints in the system to get a relationship between the displacements of block of mass m and pulley of mass M.? Homework Equations ∑T.a= 0 The Attempt at a Solution Assuming tension in both strings to be T . -T × a1 ( for the block) + 2T × a2 ( for the...
  18. navneet9431

    Laws of motion while climbing a Rope

    I'm a little confused with the application of laws of motion on a man climbing a rope. Suppose a man of mass Mg is climbing a rope with an acceleration a. Rope is massless. Now if look through the frame of the piece of rope held by the man, there is a force Mg downward by man, ma downward...
  19. S

    Newton's laws of motion: A gun firing bullets....

    Homework Statement A gun fires bullets each of mass 1g with velocity of 10m/s by exerting a constant force of 5 g weight. Find the number of bullets fired per second (take g=10 m/s2). Homework Equations F=ma M1U1 + M2U2 = M1V1 + M2V2 (conservation of linear momentum) The Attempt at a...
  20. Abhimessi10

    Pulley-block-spring system

    Homework Statement [/B]Homework Equations [/B]The Attempt at a Solution In the second question at 5:32,why doesn't the block have a spring force.In FBD of 2nd block it should have been mg-(T+kx)=ma right?
  21. thebosonbreaker

    Why were Newton's laws of motion discovered so late?

    Hi, I had a thought recently which gave rise to a rather interesting query. A helicopter works and is able to fly due to Newton's third law of motion. The propellers rotate at a high speed and exert a force on the air beneath them. By N3L, the air therefore exerts an upwards force on the...
  22. Pranav

    B F=ma -- True or an Illusion....

    Imagine, There's a ball in deep space traveling with a constant velocity of 25m/s and is having mass 25kg. Now as I said, ball is traveling with a constant velocity that simply means acceleration=0 and now if we calculate the force with F=ma we will end up with 0. But if that ball collide with a...
  23. Q

    News Newton's Laws of Motion -- looking for descriptions of the series of experiments that Newton made

    Hello Everyone ! I am interesting to find descriptions of the series of experiments that Newton made for determining the laws of motion. In English of course.
  24. V

    Friction -- Newton's laws of motion

    Homework Statement A student is cleaning a block board by moving a light duster up and down as shown. (Coefficient of friction between the duster and board is ##MU## The duster will not move no matter how large the force is if ? Homework Equations No equations given The Attempt at a Solution...
  25. V

    Newton's laws of motion -- finding the velocity of a Block in a pulley system

    Homework Statement Determine the speed with which block B rises in figures if the end of cord at A is pulled down with a speed of 2ms^-1 Homework Equations Given Velocity downwards at A=2m/s The Attempt at a Solution Really stuck... Couldn't even start the question solving...I know all...
  26. V

    Newton's laws of motion -- pulley system

    Homework Statement In the situation given all surfaces are friction less pulley is ideal and steering is light. Find accn of block 2 Homework Equations Given F=mg/2 The Attempt at a Solution .[/B] Got answer as G/2 instead of G/4 ...(actual answer is g/4) Since F=mg/2 and block 1 is hanging...
  27. V

    Newton's laws of motion -- Constaint motion

    Homework Statement In the following diagram a massless pulley is pulled by a constant force of magnitude P. There is no friction between the block and the floor. The acceleration produced in the block if mass m is? PIC ATTACHED Homework Equations Took a1/2=a2 where a1 is accn of block and a2...
  28. Shardul Khare

    Understanding Newton's Laws of Motion: Exploring Block Movement and Friction"

    When a keep two blocks one over another...And apply a foce on the block which is below...Why does the upper block falls down..Why dosent it move with A? assumin there's no friction between A and B?
  29. doktorwho

    A rolling cylinder problem

    Homework Statement With the equations of motion in polar coordinates given by ##r(t)=pcos{kt^2}, φ(t)=kt^2## determine the velocity intensity of a point ##M## on the circumference of a cylinder which is rolling without friction on a horizontal plane at time ##t## is the velocity of the center...
  30. S

    The normal reaction between blocks A and B is?

    Homework Statement 2. The attempt at a solution Let rightward acceleration of the block (A+B) be $$a$$. Let downward acceleration of block (A) be $$a'$$ down. For block A: $$mg-T=ma'$$ $$N+ma=0$$ For block B: $$T+N=Ma$$ On solving $$N=-\dfrac{m^2g}{M+2m}$$ by taking $$a=a'$$.But...
  31. donaldparida

    What will be the weight measured by the balance?

    Suppose there is a beaker filled with water placed on a weighing machine. Suppose the reading is x kg. Now, if i immerse a solid block inside the beaker without touching the walls or the bottom of the beaker, will the reading given by the weighing machine increase or not?
  32. donaldparida

    Weight of pulley with mass attached to it.

    Suppose there is a pulley(of negligible mass) and a string(of negligible mass) passes through the groove and two equal masses are attached to each end of the string. Now, if the whole arrangement is attached on a spring balance what will be the reading of the spring balance. Will it be zero?
  33. Sqrt

    Laws of Motion - Problem

    Homework Statement Two cardboard boxes full of books are in contact with each other on a friction less table.Box H has twice the mass of Box G. If you push on box G with a horizontal force F, then box H will experience a net force of? 2. The attempt at a solution Let book G's mass be = m...
  34. UchihaClan13

    Is a=g/3 the only solution or are there other possible solutions?

    Homework Statement xg=x*(dv/dt)+v^2 is a differential equation Which has a solution of the form v=at Where a is a constant.Find a Homework Equations dv/dt=v*(dv/dx) V=dx/dt A=dv/dt=d^2x/dt^2The Attempt at a Solution I assumed 'a' as a function of g That is a=kg for some constant k And...
  35. ItsAnshumaan

    Find the tension in the rope

    Homework Statement In order to raise a mass 'm' a man ties it to a rope and passes the rope over a friction less pulley. He climbs the rope with an acceleration 3g/2 relative to the rope. If the mass of the man is m/2 and the mass of the rope is negligible, the tension in the rope is a) 3mg/2...
  36. A

    Newton's laws of motion -- masses on pulleys....

    Homework Statement Wasnt able to upload file, therefore an external link https://drive.google.com/file/d/0B0FIIKckKOcKWFcxcmtJRVRXZTA/view?usp=drivesdk A force F= mg is applied on C, all pullies are frictionless and we need to find the reading of the spring balance, basically the tension...
  37. Holden Kenne

    B Understanding Newton's Laws of Motion: Exploring Errors and Contradictions

    Hi, I'm a frehshman in High school writing a paper about Isaac Newton. One of my paragraphs is about the laws of motion. I came across a tidbit of information - there are instances in which Newton's laws are not correct. One example I found was that, at speeds approaching that of light, an...
  38. hackhard

    B Can Force Change Mass w/ Constant Velocity?

    can a resultant external force on a body change its mass but keep velocity of its centre of mass constant ? Is it practically possible - ##\vec{F}_{ext}=\vec{v}_{com}\frac{\mathrm{d} M}{\mathrm{d} t}## where F is nonzero
  39. A

    Question based on laws of motion (inclined motion )

    Homework Statement what is the value of F needed so that block begins to move upward on frictionles incline plane . Homework EquationsThe Attempt at a Solution i made an attemp and got the answer - Mgtan(thetta) but the real answer is - mgtan(thetta/2)
  40. B

    Problem with making the correct FBD

    Homework Statement Consider a wedge of mass ##m## whose upper surface is a quarter circle and is smooth. The lower part is rough. A small block of same mass is kept at the topmost position and the initial position is shown in figure. The block slides down the wedge. Find the minimum value of...
  41. AveryB

    Help with Newtons laws of motion and force?

    If anyone could tell me how to answer these questions that would be fantastic. Thank you so much! 1. A box that weighs 66.2 N on Jupiter is taken to Pluto. The weight of the box on Pluto will be ____. (acceleration on pluto is 0.42) Would you find the mass first? 2. The hand in the image...
  42. B

    Maximum extension of a spring on an inclined plane

    Homework Statement A block of mass ##M = 1 kg## is placed of a fixed rough incline of inclination ##\theta=sin^{-1} \frac{7}{10}## and coefficient of friction ##\mu=\frac{1}{\sqrt{51}}##. It is connected to a spring of spring constant 100 N/m. Initially the spring is in natural state with...
  43. B

    Understanding why change in Kinetic Energy is 0

    Homework Statement Find the minimum force ##\displaystyle F## required to move ##\displaystyle M_2##.Details and Assumptions: ##\displaystyle M_1 = 3Kg## ##\displaystyle M_2 = 5Kg## ##\displaystyle \mu_1 = 0.4## ##\displaystyle \mu_2 = 0.6## ##\displaystyle g = 9.8m/s^2## Homework...
  44. B

    Rope hanging from a table, find time taken to fall off table

    Homework Statement A rope of uniform mass per unit length ##\lambda## and length ##L## lies curled on a table, with a short length ##\delta l## of it hanging through a hole in the table. At time zero, the rope begins to slide through the hole. At what time ##t_c## (in seconds) does the end of...
  45. B

    2 sphere system, Conservation of Energy and Momentum

    Homework Statement [/B] A sphere of radius $1m$ and mass $25 Kg$ is put on another sphere of radius $5 m$ and $7 Kg$ which is placed on a smooth ground. Now the upper sphere is pushed very slightly from it's equilibrium position and it begins to fall. Now when the line joining the centre of...
  46. W

    Finding the velocity change before colliding

    Homework Statement Two identical blocks of mass M are tied with a mass-less string of length L. If the string is pulled with a force F right at the midpoint of string L, the blocks will move towards each other. What will the velocity be when the blocks collide. The blocks start from rest and...
  47. S

    Newton's laws of motion problem -- Knife penetrating cardboard

    An open knife edge of mass 200 g is dropped from height 5 m on a cardboard. If the knife edge penetrates distance 2 m into the cardboard, the average resistance offered by the cardboard to the knife edge is:
  48. Rinzler09

    Proof of T.a=0 rule in mechanics (Laws of motion)

    There is this T.a rule in laws of motion which can be applied to a system to solve problems regarding constraint motion. Here's an example This example is pretty simple so I've decided to show the application of the rule here. Consider the FBD of m, T is in the same direction as the...