What is Ball: Definition and 999 Discussions

BALL (pronounced "ball") is software consisting of the versatile C++ class framework Biochemical Algorithms Library (BALL), a set of algorithms and data structures for molecular modelling and computational structural bioinformatics, a Python interface to this library, and a graphical user interface to BALL, the molecule viewer BALLView.
BALL has evolved from a commercial product into free-of-charge open-source software licensed under the GNU Lesser General Public License (LGPL). BALLView is licensed under the GNU General Public License (GPL) license.
BALL and BALLView have been ported to the operating systems Linux, macOS, Solaris, and Windows.
The molecule viewer BALLView, also developed by the BALL project team, is a C++ application of BALL using Qt, and OpenGL with the real-time ray tracer RTFact as render back-ends. For both, BALLView offers three-dimensional and stereoscopic visualizing in several different modes, and applying directly the algorithms of the BALL library via its graphical user interface.
The BALL project is developed and maintained by groups at Saarland University, Mainz University, and University of Tübingen. Both the library and the viewer are heavily used for education and research. BALL packages have been made available in the Debian project in April 2010.

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  1. ezfzx

    Ball rolling within a rolling cylinder

    Cylinders rolling down inclines are a common demo. But how do you model the movement of a sphere rolling within a rolling cylinder? I teaching a physics class and this question came up and my dynamics math is a little rusty. But I haven't found anything like this in any book or online. There's...
  2. T

    Ball hitting racket - Momentum Question (ENGAA 2017)

    Please scroll-sown to Question 52: https://www.undergraduate.study.cam.ac.uk/files/publications/engineering_s1_qp_2017.pdf The correct answer is 'B'. This is the working I did: F = (change in momentum) / (change in time) change in momentum = mv - mu, where v = final velocity and u = initial...
  3. B

    Solving the Mystery of the Ball & Beakers: Determining the Layers of Fluids

    a) I think in the beaker with A and B, A must be the top fluid and B must be the bottom. The ball sinks through the top layer but not through the bottom. In the second beaker (B and C), it does not sink through either layer. Therefore, both B and C are more dense than the ball. So B must be...
  4. TonyCross

    Calculating Theoretical Reaction Force of Ball Traveling in Semi-Circle

    Summary:: Theoretical reaction force due to ball traveling in a semi-circle circum Hi, Can anyone please help me with the following question: Setup... 1 x length of pipe bent 180 degrees with an inner diameter of 22mm, it's radius is 2mtrs, the mass of this object is 100kg. Total length of...
  5. B

    Net force acting on a ping-pong ball

    w= 0.50N, Fn= 7.8N, angle= 29 Fnet= Fn*fd* costheta = 7.8*0.50*cos(29 = 3.41 is my answer correct
  6. E

    Is this formula for a ball rolling down a ramp incorrect?

    I've got to do an experiment that essentially involves rolling a ball bearing down a (frictional) ramp and measuring its acceleration. It's quoted in the manual that the linear acceleration of a ball bearing rolling down a ramp at angle ##\theta## is ##a = \frac{5}{9} g \sin{\theta}##. When I...
  7. A

    Need help finding the launch angle of a ball

    the mass is 0.8kg speed is 50m/s distance is 100m
  8. A

    A bouncing ball hits a blob of putty on the rebound upward

    Please someone help me
  9. E

    Ball on a rotating inclined plane

    I have problems to even start with this exercise.
  10. T

    A ball thrown at an angle above an inclined plane

    I understand how the diagram below determined the ##x## and ##y## axis for the velocity vectors but I don't understand the gravity vectors. What I don't understand about the gravity vectors is why is ##-mg## in the ##y-##axis equal to ##-mg\cos\theta## and the ##x-##axis is equal to...
  11. Like Tony Stark

    Two rods, each with a free and a fixed ball and a spring

    Since there are no external forces, the angular momentum (##L##) and linear momentum (##P##) are conserved. Let's call the left rod ##A## and the right one ##B##. If all the balls were fixed, I'd write ##L_0=L_f## ##L_A+L_B=(I_A+I_B)\omega_f## From this equation I can find the final angular...
  12. A

    Ball hits a pivoting rod, what torque changes the angular momentum of the ball?

    Okay, i know that as a ball collides with a pivoting rod on an axis, the ball has angular momentum. Therefore after the collision, the ball is stopped or slowed, and the rod swings. The ball provides a force and torque to the rod. But if I isolate the ball, isn't the only thing acting on the...
  13. aspodkfpo

    Change in radius over time for a spherical ball formula

    Algebra in this answer does not seem to flow right. Firstly, the 16, secondly the n term. Can someone explain or show me the right answer?
  14. T

    Lift, Drag, Magnus, Bernoulli, Tennis ball fuzz, etc.

    Hello, My background is not fluid mechanics. Yet, I am trying, very late in life (near retirement) to understand some things, now that I have time. I have always been confused about the qualitative descriptions about the role of dimples on golf balls and fuzz on tennis balls. Sometimes, the...
  15. enthusiast

    Mechanics: A bowling ball is thrown and rolls with slipping

    Summary:: A bowling ball is thrown on a bowling lane with the coefficient of friction ##\mu## with an initial velocity of ##v_0## and no rotation. After hitting the ground, it starts rolling with slipping. After how much time after hitting the lane will the ball stop slipping? What will be its...
  16. D

    (Conceptual Problem) Whether the ball can pass through the basket

    Is it proved that the ball can pass through the basket if the positive value of time can be found? I am sure whether I did correct or not.
  17. LCSphysicist

    Steel ball oscillating in a tube

    The problem is easy to solve, the question i have is another about static. Why when we get: F = (-A*p*γ/l)y Can't we just substitute p*a = m*g? If this is a oscillation, it will be about some equilibrium position, where the net force is zero and which was the initial position of the body, in...
  18. E

    Ball rolling in a magnetic field

    I first found the Lorentz force on the ball as a whole$$\vec{F}_m = \iiint_V \rho(\omega \times \vec{r} + \vec{V})\times \vec{B} dV = \rho \vec{\omega} \times \left( \iint_V \vec{r} dV \right) \times \vec{B} + \rho \iiint_V \vec{V} \times \vec{B} dV = Q\vec{V} \times \vec{B}$$due to the...
  19. Nexus99

    A falling rotating rod strikes a ball of mass M....

    A homogeneous rod of length l and mass m is free to rotate in a vertical plane around a point A, the constraint is without friction. Initially the rod is stopped in the position of unstable equilibrium, therefore it begins to fall rotating around A and hits, after a rotation of ## \pi ## , a...
  20. A

    Is the Coriolis Effect Real? Exploring Motion in a Tossed Ball Video

    Does ball (in video)when flying ,going in straight line or in curve line,so if I am inside this ball, will I feel like I am in car which accelarate in straight line or car which accelare in curve? I think ball is going straight,curved path is just illusion..
  21. LCSphysicist

    Succesive collisions between a ball and a wall

    Ignore the letter a. See b. I disagree with the variation of the velocity. To me, that need to be 2(Vo+V) " My point is that initial velocity before striking the wall was Vo towards the left and after the collision, the velocity is Vo + 2V towards the right, thus making the change of velocity...
  22. Superposed_Cat

    I Chance of x Red balls sharing a bucket with a Green ball

    If I have 237 buckets, and there are n green balls distributed randomly over those buckets, and I put 34 new red balls randomly in those 237 buckets, what is the formula for the probability that x green balls share a bucket with a red ball? Any help appreciated.
  23. J

    Number of dimples on a golf ball

    The approximate number of dimples is 1/(1-√(1-r^2/R^2))
  24. Z

    What happens if you put a sphere (ball) on the top of a pyramid?

    I was wondering what happens if you put a perfect sphere (a ball) on the top of a perfect pyramid. To which side will the ball fall and why? It is random? An if it is, does a pattern emerge after many attempts?
  25. T

    Ball collides with a door and pushes it open

  26. J

    Calculating Moment of Inertia from Ball Accelerations

    Hey guys. Im trying to figure out how to calculate the moment of inertia from a homogeneous ball based on a series of accelerations. The ball is released from the top of an incline plane (3.33 deg) and with a motion sensor, 5 values of acceleration where captured . Together with the radius and...
  27. Tony Hau

    Problem about a ball rolling on a rotating hoop

    [No template as this thread was moved to the homework forums after it had attracted several replies] Here I have a tutorial problem as follows: The problem I have is about part a, whose answer is as follows: When I solve the partial derivative on Vf w.r.t. r, I get Vf = mω^2rsin^2(θ)/2...
  28. E

    The work done by gravity on a ball thrown vertically upward

    It was just a conceptional question. I thought that the positive work is done while it arises and negative work is done while it falls. For the effect of air resistance, the work done on each case would be less than the work done in absence of air resistance. Is there any other things that I can...
  29. EsinDerin

    Electric Field's Force on a Suspended Plastic Ball

    Hi,I couldn't do this problem.I hope someone could help meths is my first time in this forum
  30. Bilbo B

    Ball rolling along a hoop

    If the ball's rolling on a vertical hoop placed in contact with floor and with the lowest point being the mean position of the ball undergoing to and fro motion with small angular displacement. In what ways it's time period is solved out provided the surface of the hoop is rough. If the block is...
  31. Like Tony Stark

    Calculate the period of a ball bouncing between two walls

    For A) I just have to calculate the time taken to travel from the middle to the wall and multiply that number by 4, since it travels the same distance 4 times. ##t=\frac{x_0}{v_0}## B)The energy is an exponential function ##T(n)=T_0.(1-\frac{2}{100})^n## So ##v^2={v_0}^2.(1-\frac{2}{100})^n##...
  32. IamVector

    Elastic Ball Problem: Is Something Wrong?

    anything wrong with sol or my answer?
  33. C

    Ideal Ball weight to get the maximum range from a ball launcher?

    Hello guys, i am building a ball launcher to proper a line of baits into the sea, the line has 25 baits, each bait weights 30 grams (about 1oz) ideal shooting degree seems to be 45 to get maximum range, What I would like to figure out is the ideal weight of the ball to achieve the greatest...
  34. A

    Can a pool ball come off a cushion faster than it hits it?

    Physics question help required. Can a pool ball come off a cushion faster than it hits it? - something in my distant memory tells me this breaks one of Newtons laws or something like that.
  35. S

    3d simulation of a rolling ball

    How did you find PF?: Google Hi, I'm looking for advice on how to simulate a golf ball rolling on a green. The green will have been scanned using a 3d scanner by an Engineering Surveyor. I'm trying to model putting a golf ball from any position on the green, looking for a path line to the...
  36. B

    At what angle do we have to kick a ball up the hill for n-rebounds?

    I decided to try and find a solution in a green (tilted) coordinate system. I started solving this problem with thinking about 1-rebound: ##⟹y=0, α=\text{angle under which we kick a ball}##; ##y=sin\alpha v_0t-\frac{1}{2}gt^2##; because I'm trying to solve this in a tilted system, I have to...
  37. johnconner

    B Dilating or expanding a closed ball in Riemannian geometry

    Hello. If a closed ball is expanding in time would we say it's expanding or dilating in Riemannian geometry? better saying is I don't know which is which? and what is the function that explains the changes of coordinates of an arbitrary point on the sphere of the ball?
  38. kaloyan

    Kinetic energy of a ball rolling down a ramp

    Consider the situation in the attached photo. The kinetic energy in A is 10 J, in B is 30 J. What is the kinetic energy in C? Using that the mechanical energy is the sum of potential energy ##(E_p=mgh)## and kinetic energy ##(E_k=\dfrac{mv^2}{2})##, we get that the mechanical energies in...
  39. T

    What happens to a ball thrown forward vs. backward in a moving train?

    Can someone answer this question? If I throw a ball forward and another one backward (opposite to the train's movement) in a moving train, do both balls land at an equal distance from the thrower? I suspect throwing a ball forward is the same as throwing it in a motionless train but what about...
  40. Amik

    Conservation of momentum when a ball hits a wall

    I think we can.Although the wall is not moving, it is just because the wall has a huge mass.As rhe law of the conservation of momentum states(suppose the ball hits the wall from the left), when the momentum decrease by J, the momentum of the wall increase by J, which means the momentum of the...
  41. P

    Charged metal ball wrapped in rubber or other insulator

    If I have a metal electric conducting ball the size of an average snowball (Happy Holidays) and give it a charge of say 0.1 Coulombs and set it on a wooden table, will it ever discharge if not touched by anything else? If so, if it is wrapped in an electrical insulator, will it ever discharge...
  42. M

    Modeling a ball thrown vertically including drag from air resistance

    So I'm trying to figure out how to model a ball getting thrown vertically with the starting velocity v_0. So I've come up with a differential equation which I'm pretty sure is correct: Where D is a constant. So far so good. My problem is solving this. This is my attempt: And when i do this...
  43. A

    Magnetic levitation of a ball within a transparent tube

    Hi, after reading much interesting information on the subject I want to made a small project, the idea is to have a transparent plexiglass tube and a (diamagnetic?) material ball within the tube and to have permanent magnets outside the tube in such a way that I can suspend the ball so that it...
  44. Shuja

    How to Design a Ball Throwing Mechanism That Only Intakes One Ball at a Time?

    So I am designing a mechanism where balls have to be fed from a feeder into a mechanism which can only intake 1 ball at a time. I have thought of multiple designs but all of them end up having the same problem i.e. the entry hole is choked if 2 balls try to enter at the same time. Does anyone...
  45. B

    MHB Finding Time for a Kicked Ball

    Problem: You are playing soccer with some friends while some people nearby are playing hide and seek. When the seeker gets to '4', you kick the soccer ball high in the air. WHen the seeker says '5', the ball is 10 ft in the air. When the seeker gets to '7', the ball is 20 feet in the air. How...
  46. barryj

    Linear and angular momentum problem: Ball hitting a rod

    Homework Statement:: Ball of mass mb and velocity vb hits rod of length L , Rod pivots about the center. What is the angular momentum aafter impact? Homework Equations:: I = 1/12 (mR^2) I = mR^2 See the attached figure. I understand the concept of linear and angular momentum separately but I...
  47. O

    Comp Sci Ball rebounding off of a wall

    My attempts involved using suvat equations to determine the rebound distance : S = 0.5 * (u + v)*t With u being 50 and v being 0 t being time taken to fall down (Height of impact / gravitational acceleration) t = 48.41 / 9.81 Plugging the numbers in gives S = 123.365m This is where i get...
  48. Lidor

    A force exerted on a plastic ball in a rubber tube

    Hello, How can I calculate the force that must be exerted on a ball inside a rubber tube? Thanks
  49. jisbon

    Free body diagram -- Ball rotating on one arm of a Y shaped pole

    To start off with, I can't seem to interpret the FBD here. Here are my drawing: and what I interpret as. From here, I feel like I can (it's wrong obviously but I'm not sure why) state that sin theta = o/h = o/mg = N/mg , so N= mg sin theta? Thanks
  50. P

    The energy of a ball shot upwards

    a) E(mech)=E(k)+E(g) E(mech)=1/2mv^2+(0.2)(9.8)(0) E(mech)=19.6 J b) E(mech1)=E(mech2) E(k)+E(g)=E(k)+E(g) E(g)=E(k)+E(g) 0=1/2mv^2+(mgh) *No height is given so I can't solve using this method. It says instantaneous velocity meaning the velocity at...
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