What is Kinematics: Definition and 1000 Discussions

Kinematics is a subfield of physics, developed in classical mechanics, that describes the motion of points, bodies (objects), and systems of bodies (groups of objects) without considering the forces that cause them to move. Kinematics, as a field of study, is often referred to as the "geometry of motion" and is occasionally seen as a branch of mathematics. A kinematics problem begins by describing the geometry of the system and declaring the initial conditions of any known values of position, velocity and/or acceleration of points within the system. Then, using arguments from geometry, the position, velocity and acceleration of any unknown parts of the system can be determined. The study of how forces act on bodies falls within kinetics, not kinematics. For further details, see analytical dynamics.
Kinematics is used in astrophysics to describe the motion of celestial bodies and collections of such bodies. In mechanical engineering, robotics, and biomechanics kinematics is used to describe the motion of systems composed of joined parts (multi-link systems) such as an engine, a robotic arm or the human skeleton.
Geometric transformations, also called rigid transformations, are used to describe the movement of components in a mechanical system, simplifying the derivation of the equations of motion. They are also central to dynamic analysis.
Kinematic analysis is the process of measuring the kinematic quantities used to describe motion. In engineering, for instance, kinematic analysis may be used to find the range of movement for a given mechanism and working in reverse, using kinematic synthesis to design a mechanism for a desired range of motion. In addition, kinematics applies algebraic geometry to the study of the mechanical advantage of a mechanical system or mechanism.

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

    Kinematics 5 -- Vectors to two particles that are going to collide....

    Homework Statement Homework EquationsThe Attempt at a Solution The two particles are supposed to move along the same line. And the two radius vector could be anything. Is this correct?
  2. Pushoam

    Kinematics 4 -- Calculate the velocity from the position versus time graph

    Homework Statement Homework Equations vav = total distance traveled/ total time taken The Attempt at a Solution I have a problem in part c . How am I supposed to solve it? Is there any standard way to solve it?
  3. G

    1D Kinematics problem with a plane taking off

    Homework Statement An Airbus 380 needs to reach the velocity of 280 kmh^-1 before it takes off. The maximum acceleration the plain reaches in the runway is 0.95 ms^-2. Verify THAT the plane can use an airport with this runways. Runway 1: 3805 meters (SSW-NNE) Runway 2: 2400 meters (S-N)...
  4. C

    Cannonball - time required to stop its horizontal motion

    Let's imagine that we fire a cannon located on a platform high above the ground and we want to compute the time after which the horizontal velocity of the cannonball will be zero. Let's assume that we shoot at 0 degree angle. 1. Air resistance force F = C_d \frac{\rho v^2}{2}S 2. Assuming that...
  5. C

    Finding the wind-resistance force

    Imagine such situation: There is a sniper who fires his rifle, the bullet travels at the initial speed of, say, 1400 m/s. His target is standing 2000 meters away and the wind is blowing at 30 m/s opposing the bullet's motion. Let's assume that the bullet is fired in a straight lane and it may...
  6. A

    Kinematics Equations: When to Use Each?

    I would greatly appreciate it if someone can clarify the conditions on when to use to each of the kinematics equations, because I end up with the wrong answer for using the wrong equations of the 3. 1. vf = vi + at When can I use this and when cannot? 2. vf^2 = vi^2 + 2a(xf-xi) When can I use...
  7. R

    Mechanical energy to kinetic energy storage....?

    Can there be a system that utilizes mechanical energy to produce kinetic energy, but "storing" the mechanical energy to be used at a different time for kinetic energy? Like a bike where you pedal but don't move; that mechanical energy is waiting to be "released" by some mechanism *** exclude...
  8. P

    2-body scattering and Mandelstam Variables

    Homework Statement In a 2-body scattering event, A + B → C + D, it is convenient to introduce the Mandelstam variables, s ≡ −(PA + PB)2 , t ≡ −(PA − PC) 2 , u ≡ −(PA − PD) 2 , where PA,...,D are the 4-momenta of the particles A, . . . , D respectively, (· · ·) 2 = (· · ·) · (· · ·) denotes a...
  9. B

    Why the answer in book does not match the clue given

    Homework Statement An elevator ascends from the ground with uniform speed. At time ##T_1## a boy drops a marble through the floor. The marble falls with uniform acceleration ##9.8## m/s^2 and hits the ground ##T_2## seconds later. Fiind the height of the elevator at time ##T_1##. Clue : if...
  10. Millie Baker

    Velocity from an elastic collision

    Homework Statement A body X moving with a velocity v makes an elastic collision with a stationary body Y of equal mass on a smooth horizontal surface. Which statement gives the velocities of the two bodies after the collision? (multiple choice question)The Attempt at a Solution The answer...
  11. Nathan phisi

    Kinematics question, easier way to do this?

    Homework Statement Two cars are traveling in a straight line, in the same direction, along a multi-lane highway in adjacent lanes. Car A starts 100 m behind Car B and both cars are initially traveling with a velocity of 20 m s−1 . Car B maintains a constant velocity but Car A begins to...
  12. W

    Can somone explain this review solution (moments/inertia)?

    Homework Statement Homework Equations This would be the part I think I'm missing The Attempt at a Solution In the fourth line, Ix, where is the justification for multiplying 1/3 by the first term? I believe they are using the center of inertia of a rod, which is mr2 and the first term...
  13. W

    How to linearise this equation for experiment?

    Homework Statement I have a rotating platform that spins as a mass attached to a wheel rotates the larger platform. The mass accelerates to the ground which spins the platform essentially. I am trying to calculate the moment of inertia of another mass which will be attached to the rotating...
  14. W

    Can somone explain this review solution (vibrations)?

    Homework Statement Homework Equations The equations are all given The Attempt at a Solution This isn't really a homework question... it's solved, but I'm having a hard time following it. I don't understand where the first term: -a(kaθ) comes from. I can see it's the moment relation...
  15. D

    Calculate angular velocity of a ball rolling down incline?

    Homework Statement An 7.80-cm-diameter, 400 g solid sphere is released from rest at the top of a 1.70-m-long, 20.0 degree incline. It rolls, without slipping, to the bottom Homework Equations I=2/5 Mr^2 K = 1/2 m*v^2 Kroll = 1/2 Iw2 mgh=K+Kroll The Attempt at a Solution Using the above energy...
  16. Bunny-chan

    Understanding Motion Graphs: Converting Units and Interpreting Results

    Homework Statement I'm having some issues with the following exercise: The graph below represents the marking of a vehicle speedometer in funtion of time. Elaborate the corresponding graphs of acceleration and space traveled in function of time. What is the average acceleration of the vehicle...
  17. W

    Kinematics Belt and Pulley Problem

    Homework Statement I think I made a mistake somewhere.. Homework Equations T = Jα T = F*R The Attempt at a Solution A) I started with T = Jα Since there is no slip, αm = αL Thus: Tm / Jm = TL / JL Plugging in, we find TL = Tm * JL / Jm = 2560 Now use T = F*R. Tm = Fm * Rm Plugging in...
  18. C

    Kinematics Question: Falling object

    Homework Statement Marian, who is standing on her balcony, is surprised by a pigeon and throws a flowerpot up in the air at 2.1 m/s. It takes 3.0 s for the flowerpot to smash to the ground. The flowerpot experiences acceleration due to gravity of 9.81 m/s [down]. a) How high is Marian’s...
  19. MagdaStan

    Acceleration of the object, distance, kinematic coefficient

    Hello guys. i know i shouldn't be doing this, but I am asking you if you can help me with a problem for my younger sister, because my major is something else (biology, genetics) and she need this and doesn't know how to solve it.. 1. Homework Statement At an upper end of the slope inclined at...
  20. A

    Kinematics: The Study of Motion

    The study of motion of objects without the reference of force and mass is called...?
  21. V

    Calculating the Time for a Car Chase: Kinematics Question

    Homework Statement We have that a police car is traveling at ##26.4## m/s, and that at a time, ##t=0##, a car speeds by at ##37.5## m/s. After ##1## s, the police car accelerates constantly at ##2## m/s2. We are asked to find the time, ##t##, where the police car catches the speeder. Homework...
  22. N

    Algebra Kinematics: Ball above head, how fast must travel to

    Homework Statement Hello there physicsforums, I have a problem that I'd like feedback on as I'm not sure if I had solved it or approached it correctly. A ball that is traveling 5m/s is 30 meters above a person who is standing still. How fast must the person travel in order to catch the ball...
  23. C

    Kinematics physics lab help sources of error

    1. The problem statement of my lab I have this physics lab where I have to find the maximum velocity and maximum acceleration of a high school student sprinting/running using carbon tape and a spark timer. Which I already did. Now I'm having trouble developing my sources of error section. I hope...
  24. NoahCygnus

    Kinematics: Free fall problem.

    Homework Statement "A ball is thrown vertically upward with a speed 'v' from a height 'h' metre above the ground. The time taken for the ball to hit the ground is." Homework Equations ##s = ut + \frac{1}{2}at^2## The Attempt at a Solution...
  25. Adrian379

    What is the Work Involved in Lifting and Moving a Box with a Crane?

    1. The problem statement, all variables and given/known G=8400N h=35m d=10m g=10m/s^2 A crane elevate a box with G=8400N at h=35. After this, the box is moved horizontal on distance 10m. No friction. Work = ? ps. Sorry for bad English. Homework Equations I think that W=W1 ( work on elevating...
  26. NoahCygnus

    Kinematics: Find average speed from displacement-time graph.

    Homework Statement The problem is as follows; A boy begins to walk eastward along a street infront of his house and the graph of his displacement from the house is shown in the figure. His average speed for the whole time interval is equal to...
  27. V

    Find the linear acceleration of points on a rolling cylinder

    Homework Statement [/B] A uniform cylinder with radius r is rolling down an incline without slipping as shown in diagram below. It's angular acceleration is α and acceleration of it's center of mass C is a. What will be the linear acceleration of point of contact P and another point Q on the...
  28. C

    Calculating Frictional Force on a Roller Coaster: Solving for Final Velocity

    Homework Statement Ok so there was a question on a physics quiz I did that I have no idea how to answer. There was a roller coaster going down a hill with an initial velocity of 1.67m/s. The hill is 60m long and had an angle of 40 degrees. There is a coefficient of friction of 0.100 with the...
  29. A

    What Causes Discrepancies in Calculating Initial Angular Velocity?

    Homework Statement A wheel rotates with a constant angular acceleration of π rad/s^2. During a certain time interval its angular displacement is π rad. At the end of the interval its angular velocity is 2π rad/s. What is its angular velocity at the beginning of the time interval? Homework...
  30. C

    MHB How to Calculate Acceleration in Physics 1-D Kinematics?

    Hi everyone, So far I have loved physics but I've been having trouble moving setting up the harder questions to solve for the answer. I would really appreciate the help! Thanks! :D A car slows down from -27.7 m/s to -10.9 m/s while undergoing a displacement of -105 m. What was it's...
  31. S

    Kinematics>>Equations of Motion

    Homework Statement A motorcyclist is traveling at 15.0m/s [forward] and applies brakes. The motorcycle slows down at 5.0m/s [backward]. a) Determine the motorcycle's breaking distance [ans:23 m [forward]] Given: Vinitial: 15.0m/s [forward] a: 5.0m/s^2 [backward] Vfinal: 0 m/s [forward]...
  32. I

    Kinematics, deriving equations.

    Homework Statement "Derive the equations for position (in terms of acceleration, initial position, initial velocity, and time) and velocity (in terms of constant acceleration, a, initial velocity, v0, and time, t) from the definitions of position, velocity, and acceleration (derivative...
  33. A

    Kinematics question - friction

    Homework Statement A force of friction of 3.2N acts on a 1.1Kg puck while it is sliding along a horizontal surface. If the initial velocity of the puck was 7.5 m/s, how far will the puck travel before coming to rest? Homework EquationsThe Attempt at a Solution The answer is 9.7M. Tried...
  34. acko

    What is the speed of the shadow on the wall when a horse runs in a circle?

    Homework Statement Horse is running in circle with constant velocity V. In the middle of circle is flashlight, lighting in all directions. Wall is set as a tangent to circle. If horse starts running from tangential point and pass 1/8 of circle, what will be speed of a shadow on the wall? Can...
  35. E

    Stone launched upward - Kinematics question

    Homework Statement Laura propels a stone straight up with her slingshot. The stone strikes a tree branch 4.0m above her. It strikes the branch with a velocity of 5.0m/s. How long does this take? a= -9.81 m/s2 v1 = 5.0m/s d= 4.0 m[/B] Homework Equations d=vit+1/2at2[/B] d=v1+v2/2 x t...
  36. D

    What is the effect of slope on velocity?

    Homework Statement You are sliding downhill a slope of 10% (what angle is that?). Calculate how the starting velocity of 10 km/h changes within the first 120 s. After that you try to climb up an icy hill with 5% slope. Is that possible? Homework Equations Vf = Vi +At The Attempt at a Solution...
  37. Cameron1919

    Projectile Motion + Kinematics Clown Problem

    Homework Statement "a clown is shot of a cliff of height H at an angle theta and speed v. At the base of the cliff his friends are in a clown car. They start accelerating from rest one second after he is shot from the cannon. Assuming their car has constant acceleration, what is the...
  38. N

    Rotational kinematics of a spherical rock upon collision

    Homework Statement A small spherical rock of mass collides in space with a large spherical rock of mass as indicated in the diagram. After the collision the rocks stick together to form a single spherical object. https://postimg.org/image/fltmg3bj5/ (New here so I've no clue how to upload...
  39. E

    The Acceleration of a Sliding Collar on a Shaft

    Homework Statement For the mechanism shown, determine the speed and magnitude of the acceleration of collar C in terms of b, θ, θ-dot, and θ-dot-dot. Check the attached file for the diagram. We are given the length b and angle θ. Homework Equations ΣF=ma The Attempt at a Solution I...
  40. C

    Kepler's Law for finding velocity

    Homework Statement [/B] I need to help solving part a) Homework Equations [/B] $$v= \frac{2\pi}{T}$$ $$(\frac{T_1}{T_2})^2 = (\frac{r_1}{r_2})^3$$ The Attempt at a Solution I'm not sure where to begin really. One approach I tried was getting T_1 in terms of v_0 and plugging it into...
  41. 1

    Lagrangian of 2 rotating masses on a spring, sliding down plane

    Homework Statement 2 masses are connected by a spring. They are on a frictionless plane inclined relative to the horizontal by ##\alpha##. The masses are free to slide, rotate about their center of mass, and oscillate. 1. Find the Lagrangian as a sum of the Lagrangian for the COM motion and a...
  42. C

    Ice cube sliding off metal roof

    Homework Statement Homework Equations $$mgh = \frac{1}{2}v^2$$ The Attempt at a Solution [/B] I'm working on a). I tried using conservation of energy to get v. $$mg(c+b) = \frac{1}{2}v^2$$ $$v = \sqrt{2g(c+b)}$$ After this I'm stuck. In order to get distance from knowing the velocity...
  43. Daquicker

    Minimal altitude to start a “Suicide Burn” - variable thrust

    Homework Statement I'm trying to calculate the absolute lowest safe altitude above a planet's surface to start firing the thrusters on a simulated lander in order tot just reach vCraft = 0 at the planet's surface. The force the craft's thrusters responsible for desceleration generate is...
  44. PITPin

    Kinematics : two cars meeting

    Homework Statement Two cars leave at the same time (one from city A and the other from city B) and drive toward each other. They first meet d=45 km far from B . Both cars reach their destination (B for the former, A for the latter) and then start driving to their initial cities.The cars have...
  45. T

    Kinematics problems: Displacement in Moon & Proportionality

    Homework Statement An astronaut on the moon throws a stone horizontally with a speed V0. If the acceleration due to gravity on the moon is 1⁄6 that of the Earth, by what factor will the horizontal distance traveled by the stone, d, change? Answer Options: 2 2.44 1.20 36 6Homework...
  46. W

    Rotational Motion of a thin rod about a pivot

    Homework Statement A uniform thin rod of Length L and mass M is pivoted at one end is held horizontally and then released from rest. Assuming the pivot to be frictionless, find a) Angular velocity of the rod when it reaches its vertical position b) The force exerted by the pivot at this time...
  47. Q

    Kinematics - trajectory formula

    Homework Statement given : i need to find the trajectory formula Homework Equations i'm not sure if to use : The Attempt at a Solution [/B] I tried different options with the trigonometric identities that I have written before: thanks
  48. L

    Kinematics car braking scenario

    Homework Statement car is braking evenly. The brakes are in locking essentially (not ABS brakes) Car is sliding under sliding friction. Car comes to a fullstop at the distance of 150m starting velocity was 100km/h (27,77m/s) calculate a) braking time b)cars deceleration c) friction coefficient...
  49. A

    Time of flight objects in air versus in vacuum

    Hello I needed to know a logical answer to the question that whether the time of flight of the objects in air increases or decreases as compared to vacuum? Why?
  50. K

    Kinematics of a Thrown Ball: Finding Time to Reach Ground

    Homework Statement A ball is thrown horizontally wit speed 20m/s, from the top of the building which is 30m high. Find the time the ball takes to reach the ground? Homework Equations S= ut+0.5at^2 The Attempt at a Solution S=-30 u=0 A=9.8 T=? When I pluck the values I will get t^s=-30/4.9...
Back
Top