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. J

    How Many Meters Did You Win the Race By?

    Homework Statement You nose out another runner to win the 100.000 m dash. If your total time for the race was 11.800 s and you aced out the other runner by .001 s, by how many meters did you win? Homework Equations vavg=Δx/Δt v=x/t The Attempt at a Solution I have the answer already with the...
  2. Y

    What is the Kinematics Problem for a California Condor Carrying Carrion?

    A California Condor is approaching its nest with a large chunk of carrion in its beak. As it approaches, it makes an upward swoop, achieving a momentary upward velocity of 12.8 m/s when the carrion falls from its mouth, hitting a cliff outcropping 32.1 m below. Determine the speed of the carrion...
  3. A

    Rigid body kinematics problem: finding the velocity of the center of mass

    I have to deal with the problem of finding an expression for the kinetic energy of a rigid body. One of its point is pivoted to a point that moves arbitrarily. So in order to find an expression for the kinetic energy I use König's theorem, but I need the velocity of the center of mass. I use...
  4. F

    Solve Kinematics Problem: Car Overtaking Truck

    I need help with this problem. Any help is greatly appreciated. Homework Statement At the instant the traffic light turns green, a car that has been waiting at an intersection starts ahead with a constant acceleration of 3.40m/s^2 . At the same instant a truck, traveling with a constant...
  5. T

    Special Relativity and Kinematics Problem

    Homework Statement There are three particles along the x-axis ordered from back to front, A, C, B. A travels at 4/5c and B travels at 3/5c, the speed of particle C is unknown. What must the speed of particle C be such that A and B will arrive at C at the same time? And, at what speed will both...
  6. C

    Why does this kinematics problem seem impossible.HELP

    why does this kinematics problem seem impossible.HELP! Homework Statement If the man's mass is 70 kg, if L is 0.4 m h is 0.6 m, what is the downwards force (assumed constant) exerted by his feet during the phase A to B? State any physical law or principle you use in obtaining your answer...
  7. L

    Kinematics problem with constant acceleration

    A ball is thrown downwards from a top of a 20m building with an initial velocity of 15m/s. What equation could be used to model its height? My answer: h (t) = -4.9t2-15t+20
  8. J

    Simple block kinematics problem

    Homework Statement Block A weighs 75lbf and the coefficients of static and kinematic friction between A and the plane are both 0.50. Determine the acceleration of A under the action of the 25 lbf force when the velocity at A is (a) 8fps up the plane, (b) 15 fps down the plane. (c) Zero...
  9. T

    Max Accel of Object: Can't Find Solution?

    Homework Statement This problem seems so simple yet I don't feel there is enough information to know what is the maximum acceleration the object can travel at without tipping over. I uploaded a picture of the object along with the variables. rope AB = 6 ft Angle of AB = 78 degrees...
  10. B

    Should I Attempt the Pass? Kinematics Problem on a Car

    Homework Statement A car is behind a truck going 25 m/s on the highway. The car's driver looks for an oportunity to pass, guessing that his car can accelerate at 1.0 m/s^2. He gauges that he has to cover the 20 m length of the truck, plus 10 m clear room at the rear of the truck and 10 m at the...
  11. C

    Check work on kinematics problem

    Homework Statement A truck accelerates uniformly from rest to 48km/h in 20s, holds speed for 2 minutes, and then accelerates to 100km/h at a rate of 17m/s^2. How long does it take, from rest, to reach 100km/h and what distance it traveled in this time? The book says it takes 148.5s, and I...
  12. Femme_physics

    Kinematics problem - struggling with my calculus

    Homework Statement http://img62.imageshack.us/img62/6705/smallproj.jpg The Attempt at a Solution Basically I'm struggling to understand what am I supposed to differentiate. If it's V, which is 60, then the derivative of a number is zero. If it's a, then, a = -1.2v2 If I am...
  13. B

    Solve Kinematics Problem: Find Distance Traveled Till t=5

    Homework Statement Displacement of a particle moving in a straight line is s= 6 + 12t - 2t^2 find the distance traveled till t=5. Homework Equations firstly i am having confusion in correctly interpreting the equation. The equation gives us the displacement in 't' th...
  14. B

    Kinematics Problem and stream of people

    Homework Statement Figure 2-21 shows a general situation in which a stream of people attempt to escape through an exit door that turns out to be locked. The people move toward the door at speed vs  3.50 m/s, are each d  0.25 m in depth, and are separated by L  1.75 m.The arrangement in...
  15. J

    How to Solve a Kinematics Problem?

    Homework Statement A bird is coasting along in an easterly direction at 0.447 meters/sec when a strong wind from the south imparts a constant acceleration of 0.300 m/s2. If the acceleration from the wind lasts for 2.70 s, find the magnitude, r, and direction, θ, of the bird's displacement...
  16. T

    Solving for Acceleration in an Emergency Braking Exercise: Kinematics Problem

    Homework Statement In an emergency braking exercise, a student driver stops a car traveling at 83 km/h [W] in a time of 4.0 s. What is the car's acceleration during this time? Homework Equations The Attempt at a Solution a = (v2-v1)/t = 83/4 = 21 m/(s^2) [E]
  17. C

    2D Kinematics Problem w/ Coefficient of Friction?

    I'm really lost on how to do this physics problem because I don't really understand all the components of the problem: A 7.25 kg block is sliding at 5.45m/s on a frictionless lab bench which is 8.6m high. The block hits a 1m "rough patch" before sliding off of the lab bench, and then lands...
  18. P

    Calculus based kinematics problem.

    Homework Statement A trolley is released from rest from the top of a runway which is 8m long. The displacement, s in metres, of the trolley is given by the expression(see below) where t is in seconds. Using calculus initially determine (a) an expression for the velocity of the trolley (b) the...
  19. I

    How Does Mass Affect the Acceleration and Distance Traveled by Falling Objects?

    Homework Statement A penny with mass of 3.1 grams is dropped from skyscrapper of height 1250m. Find the objects acceleration after 5 secs. If a penny with mass 2.5g is dropped at this point how far does it travel before the first penny hits the ground? Homework Equations Kinematic...
  20. S

    How Can Physics Predict the Danger Zone for Plants from Falling Snow?

    Homework Statement So...In Central Oregon there is a winter time problem that is troublesome to gardeners having to do with large masses of snow sliding off the roof and crushing plants and shrubs on the ground. Physics (in particular 2-D Kinematics) allows us to determine some features of...
  21. P

    Help with Kinematics Problem (Two bodies in motion; one direction)

    1. A train has a length of 92m and starts from rest with a constant acceleration at t= 0s. At this instant, a car just reaches the end of the train. The car is moving with a constant velocity. At t=12sec the car just reaches the front of the train. Ultimately, the train pulls ahead of car and at...
  22. S

    Kinematics Problem: Solve for a (Vi=0, Vf=Vmax)

    Homework Statement I've attempted this problem for just Laura so far. t1 = 2.00s t2 = 10.4s - 2.00s = 8.40s vi = 0.0m/s vf at the end of 2.00s = vmax For her displacement I have a little diagram: |------------------|---------------------------| ...x.....xf = 100 -...
  23. M

    Finding the Direction and Distance of a Train's Motion Using Basic Kinematics

    Homework Statement A train moving with a constant velocity travels 135 m north in 12 s and an undetermined distance to the west. The speed of the train is 26 m/s. (a) Find the direction of the train's motion relative to north. (in degrees west of north) (b) How far west has the train...
  24. C

    Multi Phase Kinematics Problem

    1. I have been given the total distance (100m) and the total time (9.780s) as well as a speed (11.7m/s) at t1 and a final speed (10.5m/s) at the end of the given time (9.780s). The initial velocity is zero at t=0. Acceleration is constant. I am not asking for the answer, just an algebra based...
  25. W

    Easy Conceptual Kinematics Problem

    The acceleration of an object can be non-zero when the speed of the object is constant. This is true. Why? If the velocity is constant, doesn't its derivative have a slope of 0?
  26. A

    Kinematics problem that i cant seem to resolve

    Homework Statement A truck starts from rest and accelerates at 1 M/S*2 . 4 s later, a car accelerates from rest at the same starting point with an acceleration of 2.7 M/S*2 . Where and when does the car catch the truck? Homework Equations i have tried s=ut + (1/2)at^2 The...
  27. T

    Kinematics Problem: Time to Reach Maximum Height with Initial Velocity 30m/s

    Homework Statement A ball is thrown vertically upward from the ground with an initial velocity of 30 m/s. Assume the acceleration due to gravity is g = 10 m s-2. How long will it take for the ball to rise to the highest point on its trajectory? (AF:no decimals) i got v1 = 30m/s a=...
  28. U

    What Is the Initial Velocity Required for a Cannonball to Hit a Moving Target?

    Homework Statement A cannon which is at the top of a 99 m high cliff fires in a horizontal direction to a dog. The initial position of the dog is 1000 m from the cliff's base. What should be the initial velocity of the cannon if the dog is moving at constant speed of 9 m/s to the cliff...
  29. A

    Kinematics problem, ball drop.

    Homework Statement A staircase contains three steps each of 10 cm high and 20cm wide(refer attachment).What should be the minimum horizontal velocity if a ball rolling off the uppermost plane so as to hit directly the lowest plane? Homework Equations s= u*t + 1/2 a*t^2 The...
  30. N

    Simple Kinematics Problem - Is the book wrong?

    Simple Kinematics Problem -- Is the book wrong? Homework Statement Is the book wrong or do I have faulty logic? Here is the problem: An astronaut on a distant planet wants to detrmine its acceleration due to gravity. The astreonaut throws a rock straight up with a velocity of +15m/s...
  31. Femme_physics

    Integrating to solve kinematics problem, bad or good?

    My lecturer told me that it's best not to integrate when you're a new student to kinematics because it's important to understand the principles of operation-- which is why we're not using it. On the other hand, I keep being told by this forum that calculus is the true way to fathom mechanics...
  32. O

    Basic one dimensional kinematics problem, need conceptual help

    Hello all, I just came across a problem that I had previously solved. A relatively simple one. What I do not understand though is why I can use the equation that I have used so many times in this particular situation. Here it is: Homework Statement A baseball pitcher throws a baseball...
  33. N

    Can You Calculate the Required Brick Throwing Velocity to Hit a Moving Target?

    Homework Statement You are on the top of a 100m high (approximately 30 story) building. You just finished building a brick grill so the tenants of the building can have barbecues. You have one brick left and do not want have to lug it back off the roof. Luckily, you see a garbage truck with...
  34. M

    Solving Kinematics Problem: Dropped Object Distance & Height

    Reading a step-by-step problem in my Kinematics chapter; the problem states: "An object is dropped travels one-fourth its distance in the last second of the fall. What height was it dropped from? They initially use the motion equation: x= x_0 + \frac{1}{2}at^2 (sans the v(Initial)...
  35. P

    Solve Kinematics Problem Homework: Part B

    Homework Statement The attempt at a solution I have already solved for part a. It's part b that I'm having trouble with right now. Here is what I have for part b: \frac{\mathrm{d} v}{\mathrm{d} t} = a_{0} + kv dv = a_{0}dt + kvdt dv = a_{0}dt + adt \int dv = \int a_{0}dt + adt And my...
  36. A

    Archer's Maximum Range in a Building: How Long and How Fast?

    Homework Statement A picture of the problem can be seen http://images3a.snapfish.com/232323232%7Ffp733%3B3%3Enu%3D52%3A%3A%3E379%3E256%3EWSNRCG%3D335%3B%3C6%3B737347nu0mrj". Original question: An archer is standing inside a long building whose ceiling is 11 m high. The archer can shoot and...
  37. C

    Interesting kinematics problem.

    I want to find a function describing the motion of the particle undergoing the type of motion depicted. Basically it is a particle on a rotating vane (constant angular speed) and at some time it is released. The particle will move along the edge to the tip of the vane (and eventually fall off)...
  38. G

    When will Mike hit the water when jumping off a diving board on the moon?

    Hey there. I've got a physics problem that is troubling me. I feel like I should be able to do it, but i's been a while since I've done much physics and I could use some help. Homework Statement Mike jumps off a springy diving board located 10.0m above the surface of a swimming pool on the...
  39. D

    How High Was Marian's Balcony When the Flowerpot Fell?

    Thanks for all the help on the previous question, everyone. I appreciate it. :smile: I've got just another problem that has confused me. Homework Statement Marian, who is standing on her balcony, is surprised by a pigeon and throws a flowerpot up in the air at 2.1m/s. It takes 3.0 seconds for...
  40. D

    How far did Andrew travel before stopping and did he hit the fox?

    Homework Statement Andrew is driving his van to deliver groceries in Elmvale. As he travels along the highway, a fox stops on the road. Andrew is traveling at 75km/h and is 42m away from the fox when he applies his brakes. It takes him 3.4 seconds to stop. a) How far did Andrew travel...
  41. D

    2D Kinematics Problem (Projectile Motion)

    Homework Statement Hi, I'm in a calculus base physics course in college so i thought this forum would be appropriate to post this question. The question is as follows: "A cannonball leaves the end of the cannon with an initial velocity of 67 m/s. Assuming a level terrain, at what angle(s)...
  42. J

    2D Vector Kinematics Problem (projectile)

    Homework Statement A person kicks a ball h of 2.0 m above the floor. If the ball flies at some angle and lands 1.2 s later at horiz d of 6.5 m from its orig. place, calc. the orig. horiz and vert. comp.s of the ball's v. Calc. the final components of the ball's v. (Assume the ball has no horiz...
  43. R

    Help with one 2-D kinematics problem? Answer is off by 2

    Homework Statement "A motorcycle daredevil is attempting to jump across as many buses as possible. The takeoff ramp makes an angle of 18 degrees above the horizontal, and the landing ramp is identical to the takeoff ramp. The buses are parked side-by-side, and each bus is 2.74 m wide. The...
  44. P

    Solve Kinematics Problem: Find Acceleration for 2.7kg Blocks on Inclined Pulley

    Homework Statement there are two blocks on a pully connected by a cable. one is on an incline and the other hangs in the air-see attatched photo. M1 = M2= 2.7kgs ; theta =34 ; coeffcient kinetic friction=.15 find accleration Homework Equations Fmax=N(coefficient kinetic...
  45. S

    Optimizing Race Kinematics: Solving for the Fastest Time

    Hi, I am unable to figure this question. Could someone help please ? A new type of race has been proposed. The object of the race is to complete the course and stop on the finish line in the minimum amount of time. The race is exactly 1 km long. The car can accelerate at 8m/s^2 and decelerate...
  46. S

    Calculating Maximum River Crossing Distance with Initial Velocity of 30 m/s

    Homework Statement If you can hurl a ball so that its initial speed is 30 m/s, what is the widest river it can cross? v1 = 30m/sHomework Equations I am not sure with only the one variable given. The Attempt at a Solution Start with a x and y component diagram?
  47. P

    How Can I Solve This 2D Kinematics Problem?

    Homework Statement A moderate wind accelerates a pebble over a horizontal xy plane with a constant acceleration = (4.60 m/s2) + (7.00 m/s2). At time t = 0, the velocity is (4.4 m/s). What are magnitude and angle of its velocity when it has been displaced by 11.5 m parallel to the x axis...
  48. T

    Two part 1d kinematics problem. Need help, not solution

    1. A parachustist jumps from an airplane and freely falls y=49.4 m before opening his parachute. Thereafter, he decelerates at a=2.02 m/s2. As he reaches the ground, his speed is 3.11 m/s. How long was the parachutist in the air? For this one I managed to get the solution already using a method...
  49. M

    One Dimensional Kinematics Problem

    Homework Statement How far has the motorcycle traveled, when it catches the ferarri? A ferrari speeding at a constant 35m/s passes a police officer at rest. 2.0 s later, the officer accelerates in pursuit at 6.5 m/s^2. How far has the motorcycle traveled, when it catches the ferarri? I know...
  50. C

    How Does Velocity Change With Height in Projectile Motion?

    Homework Statement A ball is thrown straight upward and rises to a maximum height of y above its launch point. Show that the velocity of the ball has decreased to a factor α of its initial value, when the height is y2 above its launch point is given by y2=(1-α^2)y. Also SHOW that y2=(1-α^2)y...
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