What is Kinematics problem: Definition and 281 Discussions

In computer animation and robotics, inverse kinematics is the mathematical process of calculating the variable joint parameters needed to place the end of a kinematic chain, such as a robot manipulator or animation character's skeleton, in a given position and orientation relative to the start of the chain. Given joint parameters, the position and orientation of the chain's end, e.g. the hand of the character or robot, can typically be calculated directly using multiple applications of trigonometric formulas, a process known as forward kinematics. However, the reverse operation is, in general, much more challenging.Inverse kinematics is also used to recover the movements of an object in the world from some other data, such as a film of those movements, or a film of the world as seen by a camera which is itself making those movements. This occurs, for example, where a human actor's filmed movements are to be duplicated by an animated character.

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  1. M

    How Long Does It Take a Ball to Hit the Ground If Thrown Downward?

    Homework Statement A ball is thrown down with an initial velocity of 2.0 m/s from a height of 1.75 m, determine how long until it hits the ground. initial velocity = 2 m/s distance = 1.75 m acceleration = 9.8 m/s2 time = ? Homework Equations d=vit+1/2a(t)2 The Attempt at a Solution 1.75=2t +...
  2. I

    Kinematics problem: x(t) --> v(t) --> a(t)

    1. Problem statement: an object moves along the x-axis so it's position at any given moment is x(t) = −t3(to the third power) + 6t − 12 m. a. what is it's velocity at any given moment b. what is it's acceleration c. at what moment does the object stopsHomework Equations s=vt+1/2at2 The Attempt...
  3. N

    Solving a Kinematics Problem: Throwing a Ball to Clear a Peaked Roof

    Homework Statement A peaked roof is symmetrical and subtends a right angle, as shown. Standing at a height of distance h below the peak, with what initial speed must a ball be thrown so that it just clears the peak and hits the other side of the roof at the same height? Diagram...
  4. H

    Another Kinematics Problem (I have solution)

    Homework Statement A parachutist bails out and freely falls 59 m. Then the parachute opens, and thereafter she decelerates at 2.7 m/s2. She reaches the ground with a speed of 3.1 m/s. (a) How long is the parachutist in the air? (b) At what height does the fall begin? Homework Equations...
  5. F

    Solve Kinematics Problem: Find θ for sx = symax

    Homework Statement http://imgur.com/BPPbwpu Homework Equations s = ((v + u)*t)/2 - an equation of motion for constant acceleration, which is applicable in this situation. The Attempt at a Solution Let u be the velocity at which the projectile was launched. It is given that sx = symax. So...
  6. P

    Basic Kinematics Problem -- Backpacker's average velocity and distance....

    Homework Statement Problem reads: In reaching her destination, a backpacker walks with an average velocity of 1.34 m/s, due west. This average velocity results because she hikes for 6.44 km with an average velocity of 2.68 m/s, due west, turns around, and hikes with an average velocity of 0.447...
  7. D.Man Hazarika

    Kinematics problem -- A lift ascends from rest with uniform acceleration

    Homework Statement A lift ascends from rest with uniform acceleration of 4m/s², then it moves with uniform velocity and finally comes to rest with uniform retardation of 4m/s². If the total distance covered during ascending by the lift is 28m and the total time for ascending 8s respectively...
  8. gracy

    Accel Due to Gravity When Obj Touches Ground

    if any object touches the ground i.e standing on the ground,will there be acceleration due to gravity?if yes,then how much more can object go downward due to this acceleration as it is already on the floor or ground?
  9. R

    Kinematics Problem -- 3 particles at the vertices of an equilateral triangle

    Here's the question: Three particles A, B and C are situated at the vertices of an equilateral triangle ABC of side d at time t = 0. Each of the particles moves with constant speed v. The particle at A always has its velocity along AB, B along BC and C along CA. At what time will the particles...
  10. Satvik Pandey

    A kinematics problem in which direction of velocity keeps changing.

    Homework Statement A dog sees a rabbit running in a straight line across an open field and gives chase. In a rectangular coordinate system (L,0), assume: (i) The rabbit is at the origin and the dog is at the point at the instant the dog first sees the rabbit. (ii) The rabbit runs up the...
  11. C

    Solving for the Velocity and Height in a Difficult Kinematics Problem

    Homework Statement In the figure, a ball is thrown leftward from the left edge of the roof, at height h above the ground. The ball hits the ground 1.07 s. later, at distance d = 27.5 m from the building and at angle θ = 67° with the horizontal. (a) Find h (b) What is the velocity at...
  12. 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...
  13. 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...
  14. 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...
  15. 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...
  16. 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...
  17. 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...
  18. Adjoint

    Two moving cars (Kinematics problem)

    Homework Statement Two cars, A and B are traveling in same direction with velocities vA and vB. When car A is distance d behind car B, the breaks on A are applied, causing a deceleration a. Show that to prevent a collision between A and B, it is necessary that, vA - vB < \sqrt{2ad} Homework...
  19. 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...
  20. 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.
  21. 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?
  22. 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...
  23. 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...
  24. 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...
  25. R

    2D Kinematics Problem involving subtended angle

    Homework Statement Mortar crew is near the top of a steep hill. They have a mortar. They angle this mortar at an angle of \theta = 65° . The crew fires a shell at a muzzle velocity of 228 ft/sec (69.5 m/s). How far down the hill does the shell strike if the hill subtends an angle of \phi =...
  26. T

    How to Determine if a Particle Has Returned to the Origin?

    Homework Statement A point begins at rest at x = 0 and accelerates at 1.09 m/s^2 to the right for 10 s. It then continues at constant velocity of 10.9 m/s for 8 more seconds. In the third phase of its motion, it decelerates at 5 m/s^2 and is observed to be passing again through the origin when...
  27. T

    Kinematics Problem: Sprinter Acceleration and Velocity

    Ok so I have this problem which is most likely easy to all of you. The problem says that the first 10 meters of the 100 meter are covered in the first 2 seconds by a sprinter who starts from rest and accelerates with a constant acceleration. The remaining 90 meters are run with the same velocity...
  28. C

    Solve Kinematics Problem: Subway Train, Unbanked Curve, 15° Angle

    A subway train rounds an unbanked curve at 67km/h. A passenger, hanging onto a strap notices an adjacent strap is unused and makes an angle of 15° to the vertical. What is the radius of the turn? Relation of sines, opposite and hypotenuse of a right triangle. Opposite...
  29. M

    Dynamics Module - Kinematics Problem

    Hi, I have an basic kinematics problem I can't seem to grasp -- hopefully someone can shed some light on it for me? The acceleration, a, of an object is equal to a=s, where s is the distance from the start position. Sketch a graph representing velocity against distance, s, for the...
  30. QuantumCurt

    How High Does the Flowerpot Rise Above the Window?

    Homework Statement A cat spots a flowerpot that sails first up and then down past an open window. The pot is in view for a total of .50s and the top-to-bottom height of the window is 2.00m. How high above the window does the flower pot go? I was trying to help one of my friends with...
  31. V

    Why Did the Projectile Hit Miley Cyrus Despite Her Fall?

    On a test today I came across a rather ridiculous question, in which I chose the incorrect answer. The problem is, based on my understanding of kinematics I am unsure as to why I got it wrong.1. The question stated: Miley Cyrus (not kidding) suddenly falls out of a tree at the exact time that a...
  32. P

    Pole Vaulting Kinematics Problem

    Homework Statement A pole-vaulter leaves the ground with an upward speed of 9.5 m/s. (a) How fast is she going when she is 2.0 m above the launch point? (b) How long is required to reach this height? (c) Why are there two answers to (b)? The Attempt at a Solution Question A and...
  33. T

    Solve 3D Kinematics Problem with Homework Equations | Attempted Solution

    Homework Statement I know pictures aren't the best, but here it is. Homework Equations The Attempt at a Solution This is my work for this problem. Disregard the drawing as it isn't right. I'm not sure if I'm misinterpreting the horizontal range part or what. I feel pretty...
  34. J

    Can the Slower Cyclist Win if the Race is Short Enough?

    Homework Statement Two cyclists are in a race. One cyclist knows that he is slower, so he cheats: he removes the faster cyclist’s bike chain. The cheater starts from rest immediately with acceleration 2.5 m/s2. The faster cyclist has to take 3 seconds to replace her bike chain. She then...
  35. C

    Rocket Kinematics: Acceleration and Maximum Altitude

    Homework Statement You must determine the acceleration of a rocket so that its equipment can be designed to survive. The rocket will have a burn time of t = 30 seconds, during which time it flies has a constant acceleration a. Call this Phase 1. After the fuel is exhausted the rocket enters...
  36. M

    Kinematics Problem Homework Help

    1. A car making a 99-km journey travels 38 km/h for the first 49.5 km. How fast must it go during the second 49.5 km to average 47 km/h? 2. Homework Equations ? 3. 47=.5(38+x)
  37. F

    How Does Rotational Momentum Apply in a Combined Linear and Angular System?

    1. Problem statement 2. Related equations I = bmr^2 Energy equations (linear and rotational) 3. Attempt Part a) I know that the distance or height traveled by the box is [h - d] because center of the mass of box is just d. Initial kinetic energy of the box and cylinder is 0 and if only...
  38. D

    How Do You Solve a 1-D Motion Kinematics Problem Involving a Missile?

    Homework Statement A missile is launched into the air at an initial velocity of 80 m/s. It is moving with constant velocity until it reaches 1000m, when the engine fails. a) How long does it take it to reach 1000m b)How high the missile go? c)How long does it take for it to fall back to the...
  39. E

    2D Kinematics Problem dealing with acceleration

    Homework Statement " An airplane turns slowly for 9.2s horizontally. The final velocity of the plane is 360km/hr [N]; the average acceleration during the turn is 5.0m/s^2 [W]. What is the initial velocity of the plane?" Homework Equations a=ΔV/t The Attempt at a Solution at=Δv...
  40. A

    Solved: Kinematics Problem: Final Velocity

    Homework Statement A hovercraft is traveling 3m/s at 180 deg. The fan of the hovercraft causes a=4m/s2 at 50° for 10 seconds. Homework Equations What is the final velocity? The Attempt at a Solution v = 3cos180 - 4cos50*10?
  41. W

    What is happening in this step, kinematics problem

    Homework Statement a particle travels along a straight line and the acceleration is given by a = 30 - 0.2v determine the time when the velocity of the particle is v = 30Homework Equations \int \frac {dv}{ax+b} = \frac{1}{a} \ln (ax+b) The Attempt at a Solution This is the solution from the...
  42. D

    Need help with a kinematics problem. I'm not sure if I did it properly.

    Homework Statement 6) a helicopter blade spins at exactly 100 revolutions per minute. It's tip is 5.00m from the center of it's rotation. (a) calculate the average speed of the blade tip from the helicopters frame of reference. (b) What is it's average velocity over one revolution? radius...
  43. P

    Dynamics And Kinematics Problem

    Homework Statement Given: m = 17kg Vi = 0 Fa=42N θ=25 Mu=0.15 T=125s Diagram: http://s14.postimage.org/euy3whikh/New_Bitmap_Image.png Find: Δd a block accellerates from rest for 125s find the displacement. Frictional forces act on the block. A force applied is 25 degrees above the...
  44. S

    2d Kinematics Problem Final Velocity

    Homework Statement http://imgur.com/fGYf0 Stuck on #3 Homework Equations V = Vi + a*t Y = (1/2)gt^2 + (ViY * t) + Yi The Attempt at a Solution I have found the vertical and horizontal components and the initial velocity. ViX = 6.2 ViY = 9.922 Vi = 11.7 Yf = 0 Yi = 7 Xi =...
  45. S

    Calculating Minimum Distance for Safe Overtaking in a Kinematics Problem

    Homework Statement Suppose that a woman driving a Mercedes zooms out of a darkened tunnel at 30.3 m/s. She is momentarily blinded by the sunshine. When she recovers, she sees that she is fast overtaking a camper ahead in her lane moving at the slower speed of 13.7 m/s. She hits the brakes as...
  46. D

    How Can I Solve 2D Kinematics Problems Using the Quadratic Formula?

    Homework Statement A projectile is shot from the edge of a vertical cliff 60.0meters above the ocean. It has a speed of 100m/s and is fired at an angle of 35 degrees above horizontal. How far from the foot of the vertical cliff does the projectile land. Homework Equations Yf= Yinitial + ViT...
  47. P

    Kinematics problem, is it possible to solve with given information?

    Homework Statement A missile is launched from a silo 50m deep. After 20 seconds the engine stops, there is a 10 second period where the rocket is coasting straight up. At the end of this period, the rocket is 8000m above the ground. a) What is initial acceleration of rocket? b) What is...
  48. I

    Quick question about kinematics problem?

    Homework Statement A commuter train can minimize the time t between two stations by accelerating (a1 = 0.1 m/s^2) for a time t1 then undergoing a negative acceleration (a2 = -0.5 m/s^2) by using his brakes for a time t2. Since the stations are only 1 km apart, the train never reaches its...
  49. A

    Kinematics Problem (Find Speed)

    Homework Statement A daredevil motorcyclist attempts to leap a 48m wide gorge. At the side where the cyclist starts, the ground slopes upward at an angle of 15 degrees. Beyond the far rim, the ground is level and is 5.9m below the near rim. what is the minimum speed necessary for the cyclist to...
  50. P

    Kinematics problem, don't know how to find unknown variables

    Homework Statement A rocket is shot straight up with an initial speed at 500 m/s. Homework Equations The equations the teacher went over beforehand were Yf = 1/2 A(T)^2 + Vi(T) + Yi Vf = A(T) + Vi The Attempt at a Solution So far I have Vf = (-9.8)(T) + 500 m/s Yf = 4.9T2 +...
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