Kinematics Definition and 1000 Threads

  1. C

    Kinematics in 1D: Will Defiance Drake reach the ship or miss?

    0.25g converts into 2.45m/s^2 V(t)=Vo+AoT 1=0+2.45T T=1/2.45 T=0.4s X(t)=VoT+1/2AoT X(t)=100+0+1/2(2.45)(0.4)^2 X(t)=100.196m I don't know if this is the right methodology or how to move on from here
  2. Santilopez10

    Kinematics question on 2 planes moving relatively with each other

    So my problem isn't actually finding the components, but knowing if the initial approach I took is correct. So what I did was: At first I found that at the same instant, ##x_{B/A}=10500 m## so then I wrote the equation of motion for plane B respect to A: so $$\vec a_{B/O}- \vec a_{A/O}=\vec...
  3. jisbon

    Circular motion with kinematics

    My working: ##s=\int v## ##v= \sqrt{\frac{a_{c}}{r}}=\sqrt{\frac{a_{c}}{\frac{4}{2t+2}}}## ##s= \int_{0}^{2} \sqrt{\frac{2}{\frac{4}{2t+2}}}## My final answer seems to be wrong. Any ideas? Cheers
  4. Like Tony Stark

    Calculating the radius of curvature given acceleration and velocity

    Well, what I've done so far is calculating the magnitude of velocity and acceleration replacing ##t=2## in ##\theta (t)## and ##r(t)## so I could get the expressions for ##\dot r##, ##\dot \theta##, ##\ddot r## and ##\ddot \theta##. But that's not my problem... my problem is related to the...
  5. Santilopez10

    Intrinsic coordinates kinematics problem

    So I know that ##a_t = \frac{dv}{dt}=-ks## and ##\frac{dv}{dt}=v\frac{dv}{ds}## then: $$v dv=-ks ds \rightarrow (v(s))^2=-ks^2+c$$ and using my initial conditions it follows that: $$(3.6)^2=c \approx 13$$ and $$(1.8)^2=13-5.4k \rightarrow k=1.8 \rightarrow (v(s))^2=13-1.8s$$ What bothers me is...
  6. Adesh

    A question of kinematics involving a changing velocity vector

    The statement "at the initial moment of time v ⊥ u and the points are separated by a distance l " gives us a picture like the one which I have added in attachment. As the time passes velocity vector v would gradually change from fully vertical to fully horizontal in order to meet point B. Now...
  7. E

    Airtime for halfpipe skateboarder

    I've calculated the potential energy at the top of the halfpipe, before the boarder drops in: PE = 39.5 kg * 9.8 m/s^2 * 3.66 m = 1416 J Since the boarder would have no potential energy and all kinetic energy at the bottom of the halfpipe, KE = 1/2mv^2 = 1416 J 1/2 (39.5 kg) (v^2) = 1416 J So...
  8. B

    Kinematics- Exercise: Driving a car on a Motorway (1eq, 2variables)

    The car in front of us (2.car): ## s_2=v_0t ## The car that is accelerating (1.car): ## s_1=x+2l+s_2= \frac{1}{2} at^2 ## Now, if we substitute the equations, we get ## x+ 2l+ v_0t= \frac{1}{2} at^2 ##. I have now 1equation with 2variables (a, t)- any suggestions on how to continue?
  9. D

    Kinematics problem -- A particle is moving with changing acceleration....

    A particle, P, starts from rest at a point X and moves in a straight line with an acceleration expressed as a=4t. After 2 seconds, the particle reaches Y and it stops accelerating. The particle leaves Y with a velocity -3ms-1, and finally comes to rest at Z. (i) Find the value of t when the...
  10. Amitayas Banerjee

    What is the angle between the velocity of and the normal to the racket?

    My approach: Let us take two orthogonal axes: x, parallel to the racket's plane and y, perpendicular to it. For the ball to not spin, the components of initial velocities of the racket and the ball along x-axis must be same. Also, as the line of collision is along the normal to the racket's...
  11. D

    Calculating Vx and Vy given V, X, Y

    I have a problem where I am given a trajectory by x(t), y(t) and I am given a constant speed throught the whole trajectory. I need to find vx and vy. Equations that I am given: x(t) = 1.5 + 0.5 * t * cos(8*pi*t) y(t) = 1.5 + 0.5 * t * sin(8*pi*t) v0 = 0.5 What I have tried to do is use the 1D...
  12. aligator11

    Particle Dynamics Problem (kinematics)

    Summary: Mechanics problem related with Calculus (differential equations) Hi everyone, I would like some help in that task, if anyone would be willing to help :) Namely I have a problem from particle dynamics. "D:" means given info... so, D: m,g,h,b, miu. We're looking for v0 and S as given...
  13. D

    Kinematics problem: Determine the velocity of this car during braking

    Step 1. Integrate the function --> it comes out to -1.8t3+t2-8t+c Step 2. Figure out the integration constant --> I know that the velocity of the car is 30m/s at t=0s so making 30m/s = -1.8(0s)3+(0s)2-8(0s)+C it would seem that C is 30m/s Step 3. Calculate velocity at 4s --> V(4s)=...
  14. Memorical

    Kinematics: time for a given acceleration, deceleration and distance

    Note: Maths has always been kinda a weak point for me in school. Anyway. From hereon I'm going to talk about this in the context of a train for simplicity, even though this is actually needed for an entirely different context - but I don't think this is relevant for the problem. In terms of my...
  15. NP04

    Simple kinematics multiple choice question

    I selected A, because the ball is merely in motion due to the force of gravity (after applied force). My teacher has not concerned us with air resistance so can someone please explain why the correct answer is C? I reasoned that gravity was always accelerating the ball at -9.8 m/s^2...
  16. 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.
  17. 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
  18. 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...
  19. 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...
  20. 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...
  21. 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...
  22. ?

    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...
  23. 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...
  24. 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...
  25. 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...
  26. 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...
  27. 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...
  28. 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...
  29. 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...
  30. 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) =...
  31. 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...
  32. 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)
  33. 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...
  34. 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...
  35. 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...
  36. 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.
  37. 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...
  38. 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.
  39. 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...
  40. 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...
  41. 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...
  42. 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...
  43. 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...
  44. 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...
  45. 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...
  46. 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...
  47. 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...
  48. 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...
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