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. TheBigDig

    Energy of Two Gamma Rays Produced by Pion Decay

    So I worked out the first part and obtained ##E_1 = 478.8MeV##, ##E_2 = 459.4MeV## and ##p = 0.49 MeV/c## but I can't quite wrap my head around the second part. Normally, I'd use the equation for s but I'm confused since I don't know the angle between the gamma rays.
  2. bardia sepehrnia

    Time needed for a Force F to accelerate the crate to 2m/s? (Dynamics)

    So above is the question. The picture below is my attempt at the solution: However the answer at the back of the book suggest that T=1.929s
  3. A

    Big Yo-Yo problem (Rotational Dynamics with Kinematics? Maybe?)

    What I attempted to do first was find alpha and turn that into translational acceleration. Taking mass of yoyo * radius of spool * gravity, (3kg)(0.8m)(9.81m/s^2) yielded 23.544 N*m, and dividing by I = 7.68 kg * m^2 yielded 3.065625 rad/s^2. Finally, multiplying by r = 0.8m gave me 2.4525...
  4. D

    Can you explain Automobile Kinematics?

    im confused
  5. Avatrin

    Need book recommendation to learn kinematics and kinetics

    Hi I am trying to learn kinetics and kinematics: Euler angles Directional cosine matrices Quaternions Inertia tensors The usage of Jacobians in robotics Manipulator kinematics Eulers equations Newton-Euler equations etc My background is in mathematics, so I would like a book which takes a...
  6. M

    Finding the change in velocity from an acceleration vs time graph

    Homework Statement The graph shows the variation with time t of the acceleration a of an object (graph attached). What is the change in velocity of the object in the time interval 0 to 4s? Homework Equations a = v/t The Attempt at a Solution My initial answer was -8 m/s, by simply finding the...
  7. RodriRego

    Inverse Kinematics of a 6 DOF Robotic Arm

    Homework Statement Hello. My colleague and I have been struggling with this assignment where we have to: - Given the position and orientation of the end-effector of a robotic arm with 6 degrees of freedom get the joint angle values (inverse kinematics). The robotic arm in question is the...
  8. ?

    Rotating sphere which separates into hemispheres

    Hi all, The scenario I'm considering is a solid sphere (of uniform density) rotating with constant angular velocity when it abruptly splits into two hemispheres along a cut which contains the rotation axis. The hemispheres will begin to separate; if, for example, we consider the rotation to be...
  9. grooveactiva

    Physics kinematics problem (not homework, but my own)

    Homework Statement This is a physics problem that I made up in order to understand one aspect of kinematics in 1-dimension: A baseball is thrown straight up, leaving the hand which is 1.1 meter above the ground. It reaches a height of 12 meters. (a) What must be the speed of the baseball when...
  10. Q

    Boat with Friction: CoM / Minimum Time Problem

    Homework Statement A person of mass ##m## stands at the left end of a boat of mass ##M## and length ##L##. Both the person and the boat are initially at rest. The coefficient of kinetic friction between the boat and the water is ##\mu##. If the person starts moving to the right, what is the...
  11. Avatrin

    Programming to learn kinematics

    Hi I am learning kinematics. Topics include inertia tensors, cosine matrices, quaternions, Euler angles etc... To learn these topics well, I want to try working on something a bit more difficult than just the underlying math. That will probably keep me more motivated. So, I am looking for...
  12. Z

    What is the kinematics of a rolling disc on a tilted plane?

    So the kinematics of the contact point of a disc rolling without slip in a Cartesian plane if fairly straightforward. The velocity for the contact point is just v = ω r ev where r is the wheel radius and ev the current direction vector of the wheel. However, say that you grab the plate and...
  13. PhysicsKT

    Optimal Path for Honeybee to Reach Honey Drop in Minimum Time - No Gravity

    Homework Statement A honeybee is flying parallel to tabletop at height with velocity .With its wings it can acquire a maximum acceleration of . At an instant when honeybee is vertically above honey drop on tabletop and decides to reach the honey drop. Neglect reaction time of honeybee and...
  14. PhysicsKT

    What is the optimal angle for an ant to climb a wire and gutter?

    Here's the problem: https://i.stack.imgur.com/rUVvu.png What I did: [2]: https://i.stack.imgur.com/AX2Ye.png [3]: https://i.stack.imgur.com/K1Zbi.png To those who could not understand what I read: So basically I used some geometry to to get $l_1$ and $l_2$ in terms of $r$ and the assumed...
  15. T

    Circular Motion Application Question

    Homework Statement First problem: The speedometer in a car is driven by a cable connected to the shaft that turns the car's wheels. Will speedometer readings be more or less than actual speed when the car's whells are replaced with smaller ones? Second problem: Keeping in mind the concpet from...
  16. Lapse

    What is the final V in the vertical direction?

    Homework Statement Homework Equations Vy2 = Vyo2 + 2ayt y = 1/2(Vyo + Vy)t The Attempt at a Solution So I have "solved" this problem with both the equations above. Using the Vy2 equation I get the result of 32.83m/s. Using the other equation I get a result of zero, because Δy = (0 - 55) =...
  17. W

    Train collision (linear kinematics)

    Homework Statement A passenger train is traveling at 29ms^-1 and a freight train is traveling 360m ahead of it at 6ms^-1 in the same direction on the same track. The driver of the passenger train has a reaction time of 0.4s before he starts decelerating. What is the minimum deceleration to...
  18. W

    MHB Kinematics + Trigonometry Application (Physics 12u)

    Show that the maximum range of a projectile launched with Vi from Yi=0 is 45 degrees. (HINT: sin20 = 2sinθcosθ)
  19. T

    Basic Kinematics - shouldn't there be a constant?

    Homework Statement Homework Equations a=dv/dt, v=dx/dt, x=integ(vdt) The Attempt at a Solution We were given the above problem and solution. Everything seems very straightforward. My question is this: should the function for acceleration also include a constant, e.g. [/B] ? None of the...
  20. Z

    Kinematics in Cylindrical Coordinates

    Homework Statement A small bead of mass m slides on a frictionless cylinder of radius R which lies with its cylindrical axis horizontal. At t = 0 , when the bead is at (R,0), vz = 0 and the bead has an initial angular momentum Lo < mR sqrt(Rg) about the axis of the cylinder where g is the...
  21. C

    Hard Kinematics problem: Ball thrown into the air

    Homework Statement A person throws a ball up from a height of 1.5 meters, 3.23 seconds later, the ball hits the ground next to you. Find the maximum height the ball reaches. Homework Equations V=V(initial)+at The Attempt at a Solution This problem almost seems impossible without knowing what...
  22. M

    Struggling with Biomechanics? Get Expert Help Here!

    Hello! I am a third year kinesiology student who is struggling with her biomechanics assignment. Mind you, I haven’t studied physics or trigonometry in four years since i left high school so I really need some help.
  23. jybe

    Calculating Safe Distance for Warning: Flower Pot Falling from 21.6m Height

    Homework Statement A flower pot is knocked off a window ledge from a height d = 21.6 m above the sidewalk as shown in the figure below. It falls toward an unsuspecting man of height h = 1.71 m who is standing below. Assume the man below requires 0.300 s to respond to a warning. How close to...
  24. L

    Calculate velocity of stopping car

    Homework Statement A car moving at 20m/s starts decelerating, travels distance d, and stops. Find the car’s velocity at distance d/2. Homework EquationsThe Attempt at a Solution my brain is fried. I feel like I’m missing something obvious but I just don’t get it.
  25. opus

    1-D Kinematics: Trains and a bird

    Homework Statement Two trains, each having a speed of 30km/h, are headed at each other on the same straight track. A bird that can fly 60 km/h flies off the front of one train when they are 60 km apart and heads directly for the other train. On reaching the other train, the bird flies directly...
  26. S

    Friction and kinematics problem

    Homework Statement What minimum time is required to move a weight of mass 50 kg over a distance of 10 meters along a horizontal floor if the rope used to pull it breaks when the tension exceeds 20kgf, while a force of 10kgf is sufficient to start the weight moving or move it uniformly...
  27. J

    Conservation of Momentum (Explosion Kinematics)

    Homework Statement [/B] A 3200 kg space vehicle (including a launchable lifeboat) is traveling with a velocity of 300 m/s in a straight trajectory [East]. The lifeboat (200 kg) is fired at a speed of 1000 m/s [N of original trajectory]. a) After firing it is found that the horizontal...
  28. R

    Find the initial velocity of a water rocket (mass changes)

    Homework Statement Find the initial velocity of the boost phase (when water is coming out). Here is everything I know - Mass of rocket with no water is 0.13kg, mass of rocket with water is 1.1kg. The total length of the rocket is 0.48m. The time to the maximum point is 3.46 seconds, and total...
  29. TachyonLord

    Find the average force at distance x

    Homework Statement A “superball” of mass m bounces back and forth with speed v between two parallel walls, as shown. The walls are initially separated by distance l. Gravity is neglected and the collisions are perfectly elastic. If one surface is slowly moved toward the other with speed V...
  30. Tyrannosaurus_

    Intro kinematics problem - is this ok?

    Homework Statement On a North-South highway, a Car drives 80 km/h [N]. A SUV, that is north of the Car, is moving 70 km/h [South]. The car is to the south of the SUV. The two are separated by 20 km. Where are the two cars when they pass each other. Homework Equations Both are in uniform...
  31. PhysicsKT

    Really interesting and tough kinematics problem

    Homework Statement Three ants A, B and C are crawling on a large horizontal tabletop always occupying vertices of an equilateral triangle, size of which may vary with time. If at an instant, speeds of A and B are vA and vB, prove that vC>= vA+vB. Homework Equations Well, that's what I don't...
  32. J

    Minimum deceleration to prevent a collision

    Homework Statement At a given time ##t=0##, a car 1 moving with constant velocity ##v_{1}## breaks with constant deceleration ##d##. Another car 2 at a distance ##L## behind car 1 and traveling with constant acceleration ##a_{2}## and velocity ##v_{2}## at ##t=0## brakes immediately as soon as...
  33. Fabrizio Vassallo

    Meaning of a phrase in a kinematics problem

    1. Problem statement: "An object is thrown horizontally with an initial speed of 10 m/s. How far will it drop in 4 seconds?" Homework Equations Δx = v0x.t Δy = v0y.t + 1/2(-g)t2 The Attempt at a Solution [/B] When I first read it, I thought that 'how far' means Δx, since when someone says...
  34. J

    Optimizing Periodic Motion in an Elliptical Orbit

    Homework Statement A particle moves periodically around an ellipse of equation ##\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1##. You can assume ##a>b##. The ##x## and ##y## components of the particle's velocity can never exceed ##v## at any point. What is the minimum possible period of the...
  35. J

    Maximum and minimum speeds in a moving cube

    Homework Statement A rigid cube in the figure moves in space. At a certain time ##t## its front face ##ABCD## is vertical and the velocity of vertex ##A## is vertical down ##v## while the velocity of its vertex ##D## makes an angle with the vertical and has magnitude ##v_{2}## while lying on...
  36. J

    Acceleration of a particle on a parabola

    Homework Statement A particle moves along a parabola on the x-y plane with equation ##y^{2}=2px## with constant speed ##1000m/s##.What is the magnitude of its acceleration? Homework Equations Parametric equations ##\vec{r}=(b^{2}t^{2}/(2p),bt)##. The Attempt at a Solution...
  37. W

    MHB Kinematics Application Question - Physics 11u

    In a 100 meter race, Maggie and Judy cross the finish line in a dead heat, both taking 10.2 seconds. Accelerating uniformly Maggie took 2.00 seconds and Judy 3.00 seconds to attain maximum speed, which they maintained for the rest of the race. a)What was the acceleration of each sprinter...
  38. J

    How Late Did the Man Arrive to Catch the Train?

    Homework Statement A man arrives ##T## seconds late to a train station. He watches the last three cars of the train pass by. The next-to-the-next-to-last car takes time ##t## to pass by the passenger, the next-to-last car takes time ##t'## to pass by and the last car takes time ##t''## to...
  39. C

    What is the net acceleration of the coin on a rotating disk?

    Homework Statement A disk is initially at rest. A penny is placed on it at a distance of 1.4 m from the rotation axis. At time t=0s, the disk begins to rotate with a constant angular acceleration of 1.9 rad/s^2 around a fixed, vertical axis through it's center and perpendicular to it's plane...
  40. L

    I get two different answers when solving a kinematics problem

    1. A car accelerates for 200 meters and has an initial velocity of 2.0 m/s and a final velocity of 6 m/s. What is the acceleration of the car if this change in velocity takes 12 seconds?Homework Equations a=Δv/Δt Δx=Vi*t+.5at2[/B]The Attempt at a Solution When I solve this using the first...
  41. E

    Kinematics: find the particle's position as a function of time

    Homework Statement There is a particle that moves in 1-dimension. mass is m, force on the object is given as a function of position(x), Fx= -mω2x.(ω is constant) when t=0 particle has x0>0, and velocity is zero. find the particle's position as a function of time. Homework Equations There is a...
  42. AntSC

    Modifying Newton's Kinematic Equations for High Altitude

    I recently watched a video on youtube where a guy fires a 50 cal. rifle straight up into the air and measures the time of flight at about 100s. It got me thinking about what altitude the round reached. So I used the kinematics equations and obtained a value of 12.25km. Amazing, but I wondered...
  43. solarmidnightrose

    B Understanding Kinematics in Calculus for High School Students

    hi, I'm a high-school student that is just beginning to learn calculus. in calculus we are learning how to apply integration and diffrentiaiton methods regarding kinematics. there is this certain phrase i do not really understand in our textbook: e.g."in the second second" how am i meant to...
  44. devilish_wit

    I have a hard time with kinematics involving inclined planes

    Homework Statement Two blocks of mass m1 = 3.00 kg and m2 = 6.00 kg are connected by a massless string that passes over a frictionless pulley (see the figure below). The inclines are frictionless. Image - https://www.webassign.net/serpse9/5-p-049.gif The inclined plane is shaped like a...
  45. V

    Complex Kinematics and Dynamics

    Homework Statement Two pucks (5 kg each) made of Teflon are on a long table, also made of Teflon. Puck A is sitting at rest on the left end of the table. Puck B is 15 m away at the right hand end of the table, and is travelling toward Puck A with an initial speed of 0.5 m/s. A person on the...
  46. V

    Complex Kinematics and Dynamics

    Homework Statement Two pucks (5 kg each) made of Teflon are on a long table, also made of Teflon. Puck A is sitting at rest on the left end of the table. Puck B is 15 m away at the right hand end of the table, and is travelling toward Puck A with an initial speed of 0.5 m/s. A person on the...
  47. L

    Was the Driver Speeding Before the Crash?

    Homework Statement "Based on the following data, determine if the driver who crashed was driving over the speed limit" The relevant data given is: -A 2002 Volvo t-bones a truck in an alley with a speed limit of 20km/h -An eyewitness heard tires screech, then a loud bang, and also said the...
  48. M

    How do we find the uncertainty of v in the kinematics eqn?

    Homework Statement Given the kinematics equation v2 = u2 + 2as, find the uncertainty Δv. Given: Values of a, s, u, and their associated uncertainties. Homework Equations v2 = u2 + 2as The Attempt at a Solution I'm aware of the rules for uncertainty propagation, but what do I do in this case...
  49. alexi_b

    Finding when acceleration is zero

    Homework Statement A block of mass 2.42kg is accelerated across a rough surface by a rope passing over a pulley, as shown in the figure below. The tension in the rope is 13.9N, and the pulley is 12.3cm above the top of the block. The coefficient of kinetic friction is 0.395. A: 2.28 m/s^2...
  50. alexi_b

    How far apart are the astronaut and satellite after 8.67 minutes?

    Homework Statement A 63.8kg spacewalking astronaut pushes off a 678.0kg satellite, exerting a 156.0N force for the 0.870s it takes him to straighten his arms. How far apart are the astronaut and the satellite after 8.67min? Homework EquationsThe Attempt at a Solution I tried just finding the...
Back
Top