Newtonian mechanics Definition and 204 Threads

Classical mechanics is a physical theory describing the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars, and galaxies. For objects governed by classical mechanics, if the present state is known, it is possible to predict how it will move in the future (determinism), and how it has moved in the past (reversibility).
The earliest development of classical mechanics is often referred to as Newtonian mechanics. It consists of the physical concepts based on foundational works of Sir Isaac Newton, and the mathematical methods invented by Gottfried Wilhelm Leibniz, Joseph-Louis Lagrange, Leonhard Euler, and other contemporaries, in the 17th century to describe the motion of bodies under the influence of a system of forces. Later, more abstract methods were developed, leading to the reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advances, made predominantly in the 18th and 19th centuries, extend substantially beyond earlier works, particularly through their use of analytical mechanics. They are, with some modification, also used in all areas of modern physics.
Classical mechanics provides extremely accurate results when studying large objects that are not extremely massive and speeds not approaching the speed of light. When the objects being examined have about the size of an atom diameter, it becomes necessary to introduce the other major sub-field of mechanics: quantum mechanics. To describe velocities that are not small compared to the speed of light, special relativity is needed. In cases where objects become extremely massive, general relativity becomes applicable. However, a number of modern sources do include relativistic mechanics in classical physics, which in their view represents classical mechanics in its most developed and accurate form.

View More On Wikipedia.org
Recent contents Top users
  1. D

    Maximum Distance for Man to Stretch Spring in Equilibrium

    Homework Statement A man with mass ##M## has its string attached to one end of the spring which can move without friction along a horizontal overhead fixed rod. The other end of the spring is fixed to a wall. The spring constant is ##k##. The string is massless and inextensible and mantains a...
  2. D

    Length covered by block after collision

    Homework Statement Board ##A## is placed on board ##B## as shown. Both boards slide, without moving w.r.t each other, along a frictionless horizontal surface at a speed of ##6 \text{m/s}##. Board ##B## hits a resulting board ##C##, "head-on". After the collision, board ##B## and ##C## stick...
  3. D

    Problem with friction on weighing machine

    Homework Statement A man of mass ##80## kg, stands. on a horizontal weighing machine, of negligible mass, attached to a massless platform P that slides down a ##37^{\circ}## incline. The weighing machine reads ##72## kg. Man is always at rest w.r.t weighing machine. Calculate: (a) The...
  4. donaldparida

    Why is the net work done equal to the change in K.E. only?

    Why is it so that the net work done by a force on an object is equal to change in kinetic energy only and not any other form of energy like potential energy? Also is the work energy theorem valid for both conservative and non conservative forces.
  5. D

    Resolving Velocity Components in Constrained Motion

    I have been having some problem resolving the velocity component along the rope. My question will be clear if you read an illustration that I encountered which is very helpful in showing my doubt very clearly. In the Fig. given below the block ##'A'## and ##'B'## are connected with an...
  6. D

    Force does work -- Two masses and a pulley system....

    Homework Statement Two blocks ##A## and ##B## having masses ##m_1= 1 kg, m_2 = 4 kg## are arranged as shown in the figure, The pulleys ##P## and ##Q## are light and frictionless. All the blocks are resting on a horizontal floor and the pulleys are held such that strings remain just taut. At...
  7. D

    Time for Bead to Lose Contact: Solving for Friction and Tension Forces

    Homework Statement In the figure shown, friction force between the bead and the light string is ##\dfrac{mg}{4}##. Find the time in which the bead looses contact with the string after the system is released from rest. Homework Equations Weight of the bead ##(m_1)=mg## Friction acting on the...
  8. D

    Condition to not let the block descend

    Homework Statement In the system shown in Fig. ##2E.5 (a)##. block ##m_2## is being prevented from descending by pulling ##m_1## to the right with force ##F##. Assuming all the surfaces to be frictionless, Find ##F## Homework Equations F.B.D of ##m_1## From the F.B.D of ##m_1## we get the...
  9. A

    Help with formula and explanation

    Good Morning / Afternoon, I'm looking at a question which has been given to me and I'm trying to find out what the answer / formula would be to it. The question is as follows: A student has been asked to move a box of mass 15 kg onto a shelf that is at a height 2 m above the ground level and...
  10. M

    Newtonian Mechanics: simultaneous equations

    Homework Statement Figure 5-12 shows a block S (the sliding block) with mass M 3.3 kg. The block is free to move along a horizontal frictionless surface and connected, by a cord that wraps over a frictionless pulley, to a second block H (the hanging block), with mass m 2.1 kg. The cord and...
  11. RubiksMelia

    Calculating Velocity from a variable force.

    Homework Statement A body of mass 5 kg is acted on by a force in a straight line. The magnitude of the force after t seconds is given by (2t - 3t^2) kg wt. If the body has an initial velocity of 3ms-1 in the same direction as the force, calculate its velocity after 4 seconds. Homework...
  12. F

    I Sum of internal forces equals zero

    This is probably a very trivial question, but my brain isn't "playing ball" today so I'm hoping someone can help me with this. Suppose I have a system of ##N## mutually interacting particles, then the force on the ##i##-th particle due to the other ##N-1## particles is given by...
  13. L

    Newtonian mechanics; word problem; calculate forces

    Homework Statement Word problem. Fisherman lifts a trout with his fishing rod directly upwards. The fish is a trout. The trout's mass is 0,45Kg. The trout's acceleration is 2,5m/s^2. a) draw free body diagram for the trout b) with how great a force, does the fishing line affect the trout...
  14. C

    Newtonian Mechanics: Pully/Two Block System

    Homework Statement The blocks of mass 20.0 kg and 10.0 kg are initially at rest on the floor and are connected by a massless string passing over a massless and frictionless pulley. An upward force F is applied to the pulley. Find the accelerations a_A of block A and a_B for block B when F is...
  15. E

    B Elevator action-reaction pair/normal forces

    In the above case, the normal force exerted by the elevator on the box would be = 10kg * g + 10kg*5m/s^2, assuming g = 10m/s^2, the elevator would exert a normal force of 150N on the box. But wouldn't the box exert an equal and opposite force on the elevator resulting in no motion? I know this...
  16. O

    Analyzing a Compressed Spring System

    It's not a homework/coursework question but I did get the system from my textbook. http://puu.sh/o03h7/32cdf7cffb.jpg I solved the question by analyzing the system at different stages. Initially both objects are moving with a velocity and having some mass so their kinetic energies are the...
  17. L

    Question about momentum and kinetic energy

    First of all i am not a native speaker so i apologize for my english. Kinetic energy is velocity squared multiplied by mass, whereas momentum is just velocity multiplied by mass. I have read that the reason for this is because conservation of kinetic energy is related to symmetry of the motion...
  18. D

    Can someone give me some hints for this incline problem?

    I am sorry, I generally would show some work but I have no clue on how to start off to find angle theta. The answer is given below and I have to get it. I don't know at all how to approach this problem and unfortunately I am not too strong on my trig identities either but I will try. May some...
  19. G

    Gravitational Waves vs Tidal Effects: Exploring Nature & Inflation

    My simple description of gravitational waves is that they are due to the relativistic principle of locality, i.e. the fact that the action of gravity is not instantaneous, something that you can’t see from the tidal effects in Newtonian physics. Is it correct? I've also found a comment...
  20. P

    Effect of internal forces on the weight of a body.

    + A man is holding a closed cage on the palm of his hand with a bird in it. When the bird flies with an upward acceleration inside the cage, it feels heavier. But the force due to the bird in the cage is actually an internal force on the cage, and internal forces don't cause acceleration of...
  21. C

    A rod falling on a frictionless surface

    Homework Statement Consider a massless rod of length $L$ with a small mass $m1$ attached on one end, and $m2$ attached on the other end. The rod is initially in the vertical position at rest on a frictionless surface, with $m1$ on bottom and $m2$ on top. A small impulse is applied to the top...
  22. R

    How long would it take two planets to collide?

    So, i was on the plane going for oxford interviews and i was thinking about what i could be asked. While i was thinking i came up with this one. Suppose the Earth and the moon were at a distance α apart at rest, how long would it take for them to crash into each other. I'm only really...
  23. A

    What is the direction of hinge force?

    how to find direction of hinge force? for example ,if a disc is hinged at a point on it's circumference and is exhibiting a rotational motion due to gravity,what is the hinge force?
  24. A

    What is moments in rotational mechanics?

    i have often come across the sentence "by taking moments" in rotational mechanics, but i really don't understand ,what it is.please explain it(iam not referring to moment of inertia).
  25. A

    Calculating Angular Momentum: Axis of Rotation Explained

    about what axis is equation of angular momentum calculated(angular momentum = moment of inertia*angular velocity)? please help.
  26. A

    Doubt from rotational mechanics

    in Newton's laws of rotational motion, is the net torque calculated only about centre of mass?or is it valid for torque about any axis?
  27. A

    Doubt from rotational mechanics

    in parallel axes theorem in rotational mechanics,is it necessary that the axes must intersect the body?
  28. A

    How to Calculate the Moment of Inertia for a Half Disk System?

    in this video http://www.physicsgalaxy.com/lectures/1/44/234/Solved-Example-2#12(see only the question) the method illustrated is integration but i thought of an alternate method, moment of inertia of half disc with radius r2 is 1/2mr2^2 and that of half disc with radius r1 is 1/2mr1^2.so...
  29. A

    Understanding Friction: Exploring Friction in Circular vs Straight Road Motion

    please explain the phenomenon of friction acting on a car moving in a circular track.also explain how is this friction static and how is this friction different from the friction acting on a car moving on a straight road.
  30. A

    Direction of friction when a body moves in a circular track?

    please explain why? Take 2 cases,and explain how is the direction of friction different in these 2 cases. CASE 1:uniform circular motion CASE 2:non uniform circular motion my thought was,friction opposes relative motion,so it must be tangential to the particle at each and every point. i very...
  31. A

    Why Does the String in a Pulley System Apply a Downward Force of 2T?

    in string pulley systems(like atwood machine),the string applies a force on pulley of force 2T downwards,but why is it so? why should it apply that force? explain in detail
  32. C

    Constrained motion with movable pulley

    Homework Statement In this, if I want the acceleration constraint between M and 2M, I write $$AM+2AB$$=LENGTH OF STRING, which on differentiating twice gives $$a_{m}=2a_{2m}$$(which turns out to be correct). However, if we look closely, the, lower end of string is FIXED to the pulley A, and...
  33. C

    Velocity of boat connected by a pulley fixed at some height

    Homework Statement A pulley fixed on a wall of height h connects a toy boat with a man on the wall. The string is pulled by the man at a constant speed u m/s. Find the velocity of boat when the string makes an angle $$\theta$$ with the water. Homework Equations The question will be more...
  34. K

    Half atwood machine with accelerating pulley

    Homework Statement [/B] Consider a half-atwood machine on a cart as below, with mass m_2 attached to M via a frictionless track that keeps it pinned to M but allows it to move vertically. All surfaces (except between the wheels/ground) are frictionless, and the pulley and rope are massless. If...
  35. K

    Newtonian mechanics - hillside fired projectile

    Homework Statement A canon is burried on a hillside, so the barrel is exactly at the height of the surface. The hillside creates angle theta with vertical, where 0 degrees < theta < 90 degrees. A canonball is fired with speed v_0 perpendicular on the hillside. The angle between velocity_0 and...
  36. upender singh

    What Is the Stiffness Constant k of the Spring?

    1:question A weight W is suspended from a rigid support by a hard spring with stiffness constant k . The spring is enclosed in a hard plastic sleeve, which prevents horizontal motion, but allows vertical oscillations. A simple pendulum of length l with a bob of mass m (mg<<W) is suspended from...
  37. L

    Series of True or False questions related to Forces and FBDs

    Homework Statement True or False (Rope does not stretch and is massless): 1. A person sits on top of a suitcase, which is_on the floor. The magnitude of the normal force of the floor on the suitcase is equal to the weight of the suitcase. 2. A bucket of milk is being pulled directly up at a...
  38. N

    Cannon shooting emergency packets

    Homework Statement A cannon at ground level is shooting emergency packets to people stranded on the roof of a flooded building of height H=120 meters. The corner of the building is located a distance D=40 meters from the cannon. It is desired that the incoming packets are flying tangent to the...
  39. E

    Boltzmann Equation: Entropy & Thermodynamics

    There was an equation I saw before and I think it pertains to Boltzmann and thermodynamics. I think it describes the entropy of a system. From what I can remember, it involves the symbol omega to denote micro states, k for a constant, and a logarithm somewhere. Anyways, hopefully some one knows...
  40. E

    Confusion with work and energy

    This is something that's bugged me since I've read about it. What does it mean to say "energy is the capacity to do work"? I've read somewhere that work is some sort of integral. But I'm still confused, what do we mean when we say "the energy of object x is so and so"? I know the two quantities...
  41. TomW17

    Moments caused by centripetal force?

    Homework Statement I was thinking about different scenarios in circular motion and came to this scenario. Suppose there's a car moving in a circle around some track. Obviously it's the frictional forces between the tyres and the road which provide the centripetal force. Now, suppose there's a...
  42. C

    Classical Good books on Vectors for Newtonian mechanics?

    Hi, I'm internested in a good book that teaches vectors (and perhaps tensors?) so i can better understand books on classical/Newtoniam mechanics. I know the basics of vectors, but i still get confused when i se them in physics books and don't completely understand what's going on when physics...
  43. andro

    Analytical formulation of Newton's Laws

    Greetings historians of physics! Newton's Principia is written almost entirely using geometrical proofs and diagrams, barely using any calculus at all. It is thought that Newton was reluctant to use his calculus in this work, fearing that it would undermine its credibility and reception, since...
  44. M

    Calculating velocity of a bullet with quadratic air drag

    So this problem was a 2 part question. The first part goes as such. 1. A gun is fired straight up. Assuming that the air drag on the bullet varies quadratically with speed, show that the speed varies with height according to the equations: v2 = Ae-2kx - (g/k) (upward motion) v2 = (g/k) -...
  45. A

    Center of mass using Mach's restatement of Newtonian Mechanics

    Homework Statement Use Mach’s restatement of Newtonian mechanics to show that if we define the centre of mass of two particles according to, ⃗ r = (m1 ⃗ r1 + m2 ⃗ r2) / (m1 + m2) then the center of mass moves according to the equation, ⃗r = [(m1 ⃗u1 + m2 ⃗u2) / (m1 + m2)]t + ⃗r0 where ⃗r0 is...
  46. K

    How to calculate external force acting on a pendulum

    I am doing a physics project whose purpose involves describing the physics behind a toy. The toy I have selected is a "decision maker" which is composed of a pendulum which has a magnetically charged ball on it that swings side to side, while having a force exerted on it by magnets which change...
  47. SalfordPhysics

    Comp Sci Fortran - equation of motion, astronomical units

    Homework Statement Euler method : Plot the trajectory of a body moving under the influence of the suns gravity from initial conditions x=1, y=0, vx=0, vy=1. My trouble is figuring out my function. Homework Equations d2r / dt2 = -r/r3 The Attempt at a Solution What I have been doing...
  48. J

    Finding force and equation of motion

    Homework Statement If v(x)=ax-2, then what is its force in terms of x. What is its motion as a function of time when x=a? Homework EquationsThe Attempt at a Solution
  49. M

    A spinning space station exhibits a change in moment of inertia.

    Homework Statement A space station shaped like a giant wheel has a radius 95.0 m and a moment of inertia of 5.03✕ 108 kg · m2. A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1g. When 100 people move to the center of the...
  50. P

    Torque vs Centripetal Force: What's the Difference?

    Torque causes a system to rotate about its axis while centripetal force causes a system to rotate about the axis of the separate system that exerted the centripetal force. So does this mean that torque specifically causes rotation and centripetal force causes revolution?
Back
Top