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.

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  1. D

    Dynamics class w/o kinematics equations?

    Homework Statement My problem is I don't understand what my professor wants us to do instead. He says that we don't need to memorize any equations, namely the equations of motion, and that everything can be solved with basic principles and integration. The problem is, I have no idea how to...
  2. B3NR4Y

    Car coming to a stop kinematics problem

    Homework Statement The acceleration of a particular car during braking has magnitude bt, where t is the time in seconds from the instant the car begins braking, and b = 1.5m/s3. If the car has an initial speed of 45m/s , how far does it travel before it stops? Homework Equations There are...
  3. Fantini

    MHB Kinematics, time taken to a wall disappear

    I'm posting this because I disagree with the answer. Here's the question. You are in a train that is traveling at $3.0$ m/s along a straight horizontal railroad. Very close and parallel to the railroad there exists a wall with upwards inclination of $12^{\circ}$ with the horizontal. Looking...
  4. M

    How Do I Correctly Calculate Height Over Time for an Object on a Ramp?

    Homework Statement time = 1 seconds, 2 seconds, 3 seconds, 4 seconds, 5 seconds acceleration due to gravity = -9.8 m/s^2 Max. Height = 3 meters Homework Equations d = vit + 1/2at^2 v = d/t The Attempt at a Solution I actually have to create values myself, so that the as the...
  5. F

    Understanding Velocity vs Time Graphs for Horizontal Motion

    Quick question about translating what's on the Velocity vs Time graph into what is actually happening to the object. A cart is traveling on a straight horizontal track. So I determined that east is positive direction. So, if the velocity vs time graph is showing a negative slope of -0.2 does...
  6. M

    How to model the flight kinematics of an airplane with air resistance?

    I want to derive some equations for a 2-D airplane's motion, specifically when it lifts off and lands. Can someone show me where I can start and how I can use differential equations to develop equations like the speed/position of the airplane in its x and y components? Also, if anyone is...
  7. Fantini

    MHB Kinematics, particle on half circle

    Here's the problem. A point traversed half a circle of radius $R = 160 \text{ cm}$ during a time interval of $\tau = 10.0 \text{ s}$. Calculate the following quantities averaged over that time: (a) the mean velocity $\langle v \rangle$; (b) the modulus of the mean velocity $ |\langle {\mathbf...
  8. C

    How Do You Solve the Kinematics Ratio Problem for a Particle's Journey?

    I was given this worksheet from my teacher and well I am finding it really tough so far .. the question below is just crushing my skull .. so i would appreciate it if you guys would guide me through it "A particle projected from ground takes time 't1' to reach 15/16 H and time 't2' to cover...
  9. Satvik Pandey

    Kinematics problem on Tetrahedron

    Homework Statement 4 ants are arranged in such a way that they make up vertex of a regular tetrahedron, of side length 1m . The ants are named Calvin , Peter , David and Aron. Each ant moves at a speed 1m/s , and moves in such a way that: Calvin moves toward Peter, Peter moves toward...
  10. S

    Train Kinematics Problem

    Homework Statement Two trains, one traveling 60.0mph east and the other traveling 90.0mph west, are on the same track. When they are 10000 ft apart both train's brakes are applied. If they both have the same deceleration, what is the minimum deceleration to prevent a collision? Homework...
  11. T

    The 15 Best Kinematics Videos You'll Find on Youtube

    For anyone interested in quickly gaining a basic understanding of kinematics principles, here's a list of 15 top videos. Enjoy! 1. Position, velocity, acceleration 2. Derivative graphs 3. Force 4. Mass and inertia 1 5. Mass and inertia 2 6. Mass and inertia 3 7. Newton’s...
  12. K

    How Do You Solve a Grade 11 Physics Projectile Motion Problem?

    I'm taking grade 11 physics online for the summer time. I have a problem with this question :] An airplane flying at 50.0m/s is bringing food and emergency first aid supplies to a camp. The plane is for the pilot to drop the supplies so that they land on an "X" marked on the ground 150m below...
  13. V

    Multiple Choice Kinematics Problem

    Homework Statement Homework Equations The Attempt at a Solution ## α = v\frac{dv}{ds} ## and K is the kinetic energy . In all the four cases ## α = v\frac{dv}{ds} = mgsinθ ## where θ is the angle which the normal to the body makes with the vertical . Fig 1) K...
  14. Adjoint

    A particle moving in parabola (Kinematics)

    Homework Statement A particle is moving along a parabola y = x2 so that at any time vx = 3 ms-1. Calculate the magnitude and direction of velocity and acceleration of the particle at the point x = 2/3 m. Homework Equations Kinematics The Attempt at a Solution vx = 3 (given) y = x2 so vy =...
  15. Satvik Pandey

    Kinematics problem -- Cat chasing a mouse on a rotating disk

    Homework Statement A mouse starts running on a circular path of Radius = 28m with constant speed u = 4m/s. A cat starts from the center of the path to catch the mouse. The cat always remains on the radius connecting the center of the circle and the mouse and it maintains magnitude of its...
  16. sankalpmittal

    At what time do the two balls hit each other?

    Homework Statement A rocket is moving in a gravity free space with a constant acceleration of 2 m/s2 along + x direction (see figure). The length of a chamber inside the rocket is 4 m. A ball is thrown from the left end of the chamber in + x direction with a speed of 0.3 m/s relative to the...
  17. C

    Relativistic kinematics: when will a photon and spaceship meet?

    Hello to everyone! I cane across this problem and since I have no training in SR I can't solve it on my own, That is why I would very mutch apprecitate any help I could get. The problem: A photon and a spaceship simultaneously start at planet A and the travel in paralal towards planet B. The...
  18. A

    Calculating Missile Launch Time for 2D Kinematics Problem

    An antitank gun which fires missiles with a speed of 240m/s is located on a 60m high plateau overlooking the surrounding plain. The gun crew sights an enemy tank 2200m from the base of the plateau. Simultaneously, the tank crew sees the gun and starts to head directly away from the plateau. The...
  19. T

    Kinematics Crash Simulation Question

    1. In a crash simulation, a car traveling at x m/s can stop at a distance d m with a maximum deceleration. If the car is traveling at 2x m/s: A. Stopping time is doubled B. Stopping distance is doubled C. Stopping distance is quadrupled D. Both A and C Ok, so I thought this was a...
  20. P

    Kinematics Questions: Acceleration, Velocity, and the Speed of Light

    Hi, I have some questions regarding Kinematics: 1. If an object is accelerating at 9.8 m/s^2, how much time does it Need to reach ten percent of the Speed of light? Speed of light: 299 792 458 m / s -> 10% -> 299 792 45,8 m / s t = v/a -> 299 792 45,8 m / s / 9.8 m/s^2 = 3 059...
  21. A

    Kinematics Problem Ball throwing

    Hi, Could you please look at this problem in the picture and my steps? (check my answer) I do not have the solutions to the problem weirdly.
  22. A

    Mistakes in Kinematics Problem: A Lesson in Precision and Accuracy

    Please look at pictures. Why is it that they use 24 seconds for the time in b)? They get t=6.16s, why do they not plug that into the Dx equation to get 185m of x displacement?
  23. L

    MHB Rocketeer to the rescue: kinematics

    A determined student is dropped from the CN Tower in Toronto, 553 in, and fall librernente. Its initial velocity is zero. Rocketeer arrives 5.00 seconds after and it fall of the tower to save him. Rocketeer is has a velocity down of magnitude vo. In order to avoid injury. Rocketeer must catch at...
  24. R

    Basic Kinematics Problem -- A plane flies North with a crosswind

    [b]1. A plane is aimed north and is traveling 851 km/h. A wind blows the plane from 40° S of E at 36 km/h. What is the plane’s resultant velocity? [b]2. I think the answer is 828.3 km/h at 88.1° East of North but I am not sure. Ay= 851 Bx= cosθ cos40=x/36 x=27.6 By=sinθ...
  25. V

    Kinematics problem-finding total distance

    Homework Statement A particle moving at 5 m/s reverses its direction in 1 s to move at 5 m/s in the opposite direction. If its acceleration is constant, what distance does it travel? A) 1.25 m B) 2.5 m C) 5 m D) 10 m Homework Equations d = 1/2 (v0 + v)t The Attempt at...
  26. V

    Kinematics help-determining distance traveled

    Homework Statement A particle starts from rest and travels in a straight line for 4 s. If the particle is accelerating at a constant rate, which of the following could be the distances traveled by the particle during each consecutive second? A) 10 m, 20 m, 30 m, 40 m B) 5 m, 15 m, 25 m...
  27. S

    Kinematics: Angled Projectile Launch

    Homework Statement Determine the initial velocity of the projectile as it comes out of a cannon at a 20° angle. Homework Equations d = (Vi)(t) + 1/2(a)(t)^2 The Attempt at a Solution I've split the question into both x and y components and solved for both using the equation above...
  28. FeDeX_LaTeX

    No problem, glad I could help!

    Kinematics -- Vector DE Homework Statement The Attempt at a Solution Here's their solution. I'm stuck on (b). The first and second lines are fine. But how do they get from the second line to the third line? And then in the fourth line, why are they integrating from u^2 to v^2? EDIT...
  29. D

    Ball Drop and Projectile Motion: When Will They Meet?

    A ball is dropped from a 100m cliff. at the same time another ball is thrown up such that it has enough velocity to reach the top. at what distance from top of the cliff will the two balls meet?
  30. H

    How Does Force Angle Affect Book Acceleration with Friction?

    Homework Statement A book of mass M = .55 kg rests on a table where the coefficient of static friction us = .45. A force, F = 4 N acts on the book at an angle of 15 degrees above the surface of the table. What is the acceleration of the book if the coefficient of kinetic friction uk = .23...
  31. C

    Minimum Speed for Stunt Car Jump over Parked Cars

    Homework Statement A stunt driver wants to make his car jump over 8 cars parked side by side below a horizontal ramp (Fig. 3–41). (a) With what minimum speed must he drive off the horizontal ramp? The vertical height of the ramp is 1.5 m above the cars and the horizontal distance he must clear...
  32. C

    Basic kinematics - fox jumping over a wall problem

    basic kinematics -- fox jumping over a wall problem Homework Statement A fox is 3.2 m from a 0.5 m tall wall. If it leaps from the ground towards the wall with an initial velocity of 12.0 m/s at angle of 18.9° above the horizontal, how high off the ground will the fox be when it reaches the...
  33. P

    Analytical kinematics of a 6-bar mechanism

    Homework Statement This is a mechanism I'm working with for my undergrad project (its Modelled in Msc ADAMS) https://www.flickr.com/photos/35430110@N04/13902494524/ https://www.flickr.com/photos/35430110@N04/13902494524/ And to give you an idea of how it operates; position 1...
  34. R

    Inverse Kinematics - Obtaining the Equation of a Path

    Obtaining the Equation of a Path I'm working on a project for myself in SolidWorks which involves a scissor-type mechanism. The bottom ends of the linkages are attached to disks that are free to rotate around the central hub where all the gears are attached. On the other side of the hub is...
  35. Y

    Kinematics Question -- 2 Runners Racing Each Other

    Homework Statement Dave and Andrew are racing. Dave running at a constant speed of 20m/s is passed by Andrew. 2.0s after Andrew passes, Dave accelerates at 1.0m/s^2 until he catches up with Andrew 25s later. What is Andrew's velocity (he does not accelerate)? Homework Equations...
  36. A

    Kinematics and Work-Energy problem with skier

    Please look at attached picture. Why did my teacher assume that vf does not change upon landing in the last sub-question? This makes no sense to me. Is there such a way that the skier can change direction of vf without changing the magnitude of it? Otherwise, the skier will collide in an...
  37. W

    Kinematics Word Problem - Projectile Fired at a Stationary Vehicle

    Homework Statement A projectile is fired at a stationary vehicle. If the initial separation was 200m and the projectile traveled at a constant 75 m/s, find the acceleration the vehicle would need for a passenger to be able to reach out and calmly pull the projectile into the vehicle. (Assume...
  38. J

    Kinematics: Find Displacement in 2x Time w/ Constant Acceleration

    Homework Statement A particle has initial velocity and constant acceleration. If its velocity after certain time is v then what will its displacement be in twice of that time? Homework Equations The Attempt at a Solution Im thinking about using one of the classic kinematics...
  39. C

    How Do You Calculate Acceleration and Time for a Sprinter Reaching Top Speed?

    Homework Statement A sprinter reaches his top speed of 11m/s in t seconds from rest with essentially constant acceleration. If the maintains this speed once reached and covers the 100m distance in 11.5s, Find: a) the time it took to accelerate. b) his acceleration until he reaches...
  40. L

    Work Energy Theorem and Kinematics

    Homework Statement A small steel ball of mass .0283kg is placed on the end of a plunger of length .0051m attached to a spring 1.88m above the ground. The spring is pre-compressed .0011m and has a spring constant of 177 N/m. The plunger is then angled on a ramp 45° above the horizontal, and is...
  41. G

    Kinematics - particle acceleration and distance travelled

    Kinematics -- particle acceleration and distance travelled Homework Statement A particle moving at 10 m/s reverses its direction to move at 20 m/s in the opposite direction. If its acceleration is -10 m/s2, what is the total distance that it travels? A) 15 m B) 20 m C) 25 m D) 30...
  42. G

    Kinematics help - object is dropped from a height h

    Kinematics help -- object is dropped from a height h Homework Statement An object is dropped from a height h and strikes the ground with a velocity v. If the object is dropped from a height of 2h, which of the following represents its velocity when it strikes the ground? A) v B) 1.4v...
  43. L

    Understanding Simple Kinematics: Graphing Speed and Distance Traveled

    Hi guys, having some trouble with this question as I cannot see where I am going wrong. Very simple question but I must be misunderstanding something. Homework Statement The following table shows how the velocity of a car varied with time: Velocity (km/h) 0 19 35 48...
  44. Y

    Integrating Kinematics for Velocity from Acceleration: A Simplified Approach

    When you want to get velocity from accelleration i have been told you integrate. Howver v=at and so surley you can just multiply each term in the accelleratin expression by t. ie: a=4-0.2t Surley you can just: v=(4-0.2t)t v=4t-0.2t2
  45. A

    Velocity on a hill Kinematics Problem with Dynamics

    In the sport of luge, a competitor slides on a sled down a 500-m long straight ice track inclined at 20o to the horizontal. Her initial speed is 2.0 m s-1. The coefficient of dynamic friction between the sled and the ice is 0.050. Neglect air resistance. What is her acceleration? What is her...
  46. N

    Word Problem with Kinematics Equation

    Homework Statement An object thrown up from a cliff 10 m/s reaches a velocity of 20 m/s [down] as it lands. If acceleration due to gravity is 9.8 m/s2, what is the object's displacement? How long did it take for the object to land from the time it was thrown? Homework Equations I'm not...
  47. Darth Frodo

    How Do You Calculate the Landing Point of a Projectile Thrown from a Height?

    Homework Statement A stone is thrown with a velocity v_{0} at an angle \alpha to the horizontal (see image) from a step of height H. Calculate the x coordinate x_{1} of the point where the stone hits the ground. Homework Equations x(t) = u_{x}t + x_{0} y(t) = u_{y}t +...
  48. T

    Is this even solvable? Kinematics.

    Homework Statement A ball is thrown vertically upward from ground level with an initial velocity V0. The ball rises to a height, h, then lands on the roof of a building of height 1/2h. The entire motion requires 10s. Find the height, h, and the initial velocity, V0. Homework Equations...
  49. P

    Kinematics problem - Bullet in block of wood

    Homework Statement A 3.50kg block of wood is at rest on a 1.75-m high fencepost. When a 12.0g bullet is fired horizontally into the block, the block topples off the post and lands 1.25m away. What was the speed of the bullet immediately before the collision?The attempt at a solution d=1/2at^2...
  50. G

    Which one is more harder Dynamics Or Kinematics ?

    Hi everyone; I'm a ME student who just finished Dynamics course and I did really good. I've finished also statics course it was not easy, I faced some difficulties. So, the next semester I'll do "Kinematics and dynamics of machinery" course and I'm so worry. Is it real that Kinematics is...
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