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. rudransh verma

    B What Happens to a Ball's Energy When Thrown Upwards?

    What is going on when the ball is thrown up in the sky. It is pushed by a force F for some distance d. Then the object travels a distance s up in the sky before finally coming to a stop. So what is going on here? Is the force doing work for distance d or distance s (s>d)? I think change in...
  2. C

    I In Euclidian space, closed ball is equal to closure of open ball

    Problem: Let ## (X,d) ## be a metric space, denote as ## B(c,r) = \{ x \in X : d(c,x) < r \} ## the open ball at radius ## r>0 ## around ## c \in X ##, denote as ## \bar{B}(c, r) = \{ x \in X : d(c,x) \leq r \} ## the closed ball and for all ## A \subset X ## we'll denote as ## cl(A) ## the...
  3. Lynch101

    I Quantum Ball and Cup - Thought Experiment

    I'm sure most will be familiar with the well-known ball and cup trick. The dynamics of the game itself are unimportant, we just need to have the image of 5 cups with a single ball being revealed when the relevant cup is lifted. The Set-up Imagine a machine which has a conveyor belt coming out...
  4. M

    I Unbalanced forces acting on a ball at maximum altitude

    When a ball projected vertically upright reaches its maximum height is it instantaneously stationery (calculus provides for instantaneous events) before it starts its downwards journey? is gravity acting on the object at that instant? Newton provides that an object at rest must be subject to...
  5. rebbe90

    A rolling ball, find distance traveled

    I figured the best way to do this is to focus on the second half of time. We can use the information there to find acceleration and that should make it fairly simple to find distance traveled in the first 5 seconds. Average speed in 5s-10s I found to be 40m/s. My problem is that to find the...
  6. A

    B Problems I Have With Electrostatics and Pith Ball Experiments

    As a preliminary note, most people flex about how dumb questions and then continue to school and scold curious minds. Instead of taking a demeaning approach I just ask for respectful insight to quench curiosity. I will 1) explain the experiment as I know it to be, 2) explain what I have been...
  7. Al-Layth

    Circular Motion Problem -- Ball on a String Spinning in a Vertical Circle

    #F= m\frac{v^2}{r} = mw^{2}r# #m=5# #r=0.9# #F= 5\frac{v^2}{0.9} = (0.9)5w^{2}# #5\frac{v^2}{0.9} = (0.9)5w^{2}# #\frac{v^2}{0.9} = (0.9)w^{2}# #v=0.9w# then I get stuck cause I have both unknowns in one equations (i bet it has something to do with the question’s use of “minimum” but I...
  8. K

    Torque requirements for launching a soccer ball

    I am designing a soccer ball launcher (like the one in the attached picture) for school and am having trouble figuring out how much torque I need the motors to have. I am trying to follow an energy analysis approach to get these calculations done. Attached is a file of my calculations so far...
  9. S

    Lottery physics: ball placement and positions in lottery games

    Summary:: Lottery physics- balls placement and positions Hi all, I am not a Ph.D. in physics or even close to that, I only had some physics classes when I was at high school . the thing is that I like to examine things. I came across the lottery one time in my life and heard many assumptions...
  10. S

    I Is this statement an aspect of the Hairy Ball or Fixed Point Theorem?

    “Given any class of mutually exclusive classes, of which none is null, there is at least one class which has exactly one term in common with each of the given classes…” The reason this statement sounds like one of those theora is that I recall reading a Time-Life book on Mathematics, and there...
  11. Hendra

    Ball rolling down a slope ending with a loop

    Hello everyone! I tried to solve this problem in a non-inertial system. Probably I should use the principle of conservation of mechanical energy in the following form $$mgH = \frac{3mgR}{2} + \frac{mV^2}{2}.$$ So the only thing to do is to compute $V^2$. I tried to find this value using the...
  12. dge

    Spring compression -- Ball colliding with a spring-mounted platform

    I've tried establishing a systems of equations with -(1/2)kx^2+mpgx+(1/2)mpvp^2=0, but this leads to an annoying quadratic that when solved does not give one of the listed answers. My thought was that the spring's potential energy is going to be equal to the gravitational potential energy and...
  13. Eobardrush

    Why momentum of a ball bounced off a wall increases twice fold?

    Question 2a: It is really hard for me to get my head around this. The solution of this question mentions the momentum of the ball after it rebounds is 12kgms. My attempt at this solution is as follows Before collision Momentum of ball= mv= 2x3= 6 kgms and momentum of wall= 0 Therefore Total...
  14. A

    I Conservation of KE, wedge striking ball

    So assume we have a wedge traveling at a constant V horizontally, that is braced so it CANNOT move vertically. Ignore air and friction. See picture. It hits a stationary tennis ball and due to the angle, there is a net force on the ball as shown. The energy should come from the kinetic...
  15. Iwanttolearnphysics

    About Kinetic Energy of a ball falling vertically and bouncing up

    Hello again. I don't believe there are rules about posting twice in a day. I'm not a student and I answer Physics questions as a hobby, but I've only just started learning, so please help me out. I'm answering IBDP Physics questions. Here's my thinking: KE is not a vector quantity, so it's...
  16. san12345

    Spring potential and kinetic energy

    please help me
  17. J

    I Confirm 6ft Tall Boy Throwing Tennis Ball 🎾 in Gym

    Hello I’m hoping someone could help I was asked by a fellow student the following question A 6 foot tall boy is stood in his schools gymnasium, he throws a standard full-size tennis ball 🎾 up in the air to the height of 20 feet and it lands back into his hand at the same distance from the...
  18. Z

    What happens to a ball placed on a moving conveyor belt?

    Here is my depiction of the initial state: Note that the presence of ##f_k## means the ball is initially slipping. We also know that the linear and angular speeds of the ball are increasing in time. At some point, the ball should stop slipping. The condition for no slipping is that the speed...
  19. Elementrist

    B Magnetic force driving a small iron ball

    How can I calculate the force from magnetic field of a solenoid, grabbing a small iron ball? I want to use the good old simple F=ma formula in order to calculate the ball's acceleration. But can't find a formula to somehow convert the known field quality (in unit Tesla) to Force (in unit...
  20. JD_PM

    Spinning ball deviation from straight path | Magnus effect

    Let's focus on obtaining how much will the ball deviate from a straight path and assume the spin of the ball to be ##11600## rpm and ##C_L = 0.4## to be the lift coefficient A pitcher is able to make a baseball follow a curved path by impinging spin on the ball (which triggers nonsymmetric...
  21. Ineedhelpwithphysics

    Speeds of the rolling ball at different points in this roller coaster track

    For this question i tried to reason with my self that C was the fastest and A was the second fastest. B would be the third fastest and D would be the least fastest since the ball has to go up. I looked up the answer and it says that C is the fastest , B and D are equal, and A is the slowest. How...
  22. A

    B Projectile motion — Thinking about forces on a curve ball

    When a ball is thrown such that it moves in a curved trajectory in the horizontal plane, it amuses me to think of its dynamics. In motion of a ball thrown upwards the force of gravity gives it a parabolic trajectory However when the ball is thrown to curve and hit a target, (in the horizontal...
  23. S

    MHB Momentum of Falling Ball X & Ball Y: A Physics Puzzle

    Ball X has mass 0.03kg. It falls vertically from rest from a window that is 30 m above the ground. Ball Y has mass 0.01kg. At the same time that Ball X starts to fall, Ball Y is projected vertically upwards from ground level directly towards Ball X. The initial speed of Ball Y is 20 m/s...
  24. G

    Movement of a Ball Bearing within a cavity inside a Projectile

    Summary:: Question concerning the behavior of a ball bearing inside a projectile fired straight up or at an arc. Within a projectile is a 1-inch cylindrical cavity, inside of which is a steel ball bearing that can freely roll along the length of the cavity. When the projectile is fired...
  25. N

    Find the Length of a Pass of a Soccer Ball

    A soccer player passes the ball from a pointthat is 18 yards from the endline and 12 yards from the sideline. A teammate who is 42 yards from the same endline and 50 yards from the same sideline receives the pass. How long is the pass? I am suppose to use the distance formula for points. I will...
  26. D

    Energy, work, power and efficiency when throwing a ball upward

    I don't have an idea of where to start. I tried to do Ein = 1/2 mv^2 ------ (1/2)(1)(10)^2 ----------- 50 but i don't know where to go from here
  27. C

    Ejection speed and travel distance of a ball in a pressurized water pipe

    Diameter of metallic ball : 3.000 inches SG of ball is : 2 ID of pipe is : 4.05 inches ID of seat : 2.885 inches Pressure behind ball when released from seat #1 is 1100 psi Fluid in pipe is Seawater (above and below the ball) Fluid flow rate after ball is released is 800 litres pr minute The...
  28. C

    What type of ball can bounce and travel the most?

    From what I have investigated, I know that dimples do a large part of the process of going far, and elasticity for sure is something of the main bounce thing, but things that confuse me like if the ball is empty affects both characteristics, or if the same dimples affect the bounce of the ball...
  29. F

    A ball climbing a ramp while "rolling the wrong way"

    This image represents the ramp. The first part is pretty easy. The red part has friction, and the ball rolls down it. The blue part has no friction, and the ball climbs it only owing to the translational kinetic energy that it gained at the bottom of the red ramp, which is only a fraction of...
  30. E

    Restoring force on a ball connected to two rubber bands

    Hello there, I am wondering, in this solution, I guessed that the restoring force is given by that equation in the problem because the vertical component of the force acting on the ball is -2Tsin(x). since sin(x) = y/L with L being the hypotenuse part of the triangle formed by displacing the...
  31. F

    Momentum of a ball bouncing off of the floor

    ##m=.3 kg, v = 11 \frac {m}{s}, t = .25 s, \vec v_1 = mv\langle cos(-55), sin(-55) \rangle, \vec v_2 = mv\langle cos(25), sin(25) \rangle## $$m\vec v_1 - m\vec v_2 = \vec Ft = mv\langle cos(25)-cos(-55), sin(25)-sin(-55) \rangle$$ $$Ft = mv\sqrt{(cos(25)-cos(-55))^2 + (sin(25)-sin(-55))^2}$$ $$F...
  32. P

    Derive the period of a Ball rolling in a Bowl

    The following attempt gives the wrong answer, and I would like to know where it goes wrong. Let ##\theta## be the angle of the ball with the vertical passing through the centre of the bowl, and ##\phi## be the angle the ball rolls through. Let ##m## be the mass of the ball, ##r## be the radius...
  33. Kyran

    B Is a black hole a massive ball of photons?

    Black holes suck things in and the current explanation is that they bend spacetime. I have my own hypothesis though. If electrons shoot out photons when they switch positions in the atom that would mean that at the very least electronshave photons in them. Atoms always try to have the right...
  34. A

    How to make the small ball slide into the groove in Simscape multibody

    Good day All! I have a problem , I could do almost all the mechanism, my problem is how to make slide the little ball into the groove. whenever i run the program i got the follwing error message ['rotating_groove_cylinder_good_trial']: The following errors were found in the model...
  35. G

    Plasma ball and effects luminous

    Are the effects luminous we see in plasma ball come from electron or ions ? Or the two ?
  36. docnet

    Is there a smooth function in the unit ball with compact support?

    Is there a function that takes positive values only in the unit ball not including the boundary points defined by the set ##\{x^2+y^2+z^2<1\}##, and ##0## everywhere else?
  37. D

    B 2D Model of the Universe as an expanding ball

    Can a simplified 2D model of our universe be an expanding ball? Where the surface of the ball is the 2D universe time is the vector normal of the ball measured in imaginary number i. So light will move at 45 degree to any vector normal. The expanding ball gets bigger because time is causing it...
  38. Xlotic

    Timing a bouncing ping-pong ball

    When I throw a ping-pong ball as free fall(not in projectile motion), the time is same from t0 to t1 and from t1 to t2. How can this be possible? Or is there any necessary assumption to prove it?
  39. A

    Ball launcher question - ENERGY

    I got 12/12 on the above part^ And as for the mathematical solution below I got 5/6 and then 2.5/3 for the conclusion.
  40. W

    Can Work-Energy Formula Be Used to Solve Ball-Spring Collision?

    I completely missed the collisions approach when I first tried to solve this and tried using the work-energy formula. I am wondering if this approach can be made to work? Here is my attempt: So I let the work done on the ball be ##W_b## and work done on spring be ##W_s##. Then $$W_b=\Delta K =...
  41. G

    Question about Plasma Ball (can I leave it running all night?)

    Hi there! I wanted to know if i can leave the Plasm Ball turned on all night in my room without any problem. Thanks in advance!
  42. Alekkk

    Simulating an elastic bouncy ball

    I am trying to program a game in which I have a bouncy rubber ball which upon collision with the ground, will have a squeeze factor (like a spring) and will bounce back higher due to spring physics. I have currently been able to make a rigid bouncing ball since that simply follows the rules of...
  43. I

    Bowling Ball is rolled down a steep hill

    I have no idea how and what to do.
  44. P

    Why is static friction not considered in the work-energy theorem?

    My question is this: - Friction exists (for no slipping/pure rolling to occur) - Why is the work done against friction not accounted for in the conservation of energy equation? Thank you!
  45. N

    Pool Ball Physics: Questions on Impact Spins

    1) Can the contact between two pool balls impart any kind of spin, other that about its horizontal axis due friction contact with the table surface? 2) If a ball is in motion (traveling in a straight line) and contacts a cushion, can that contact impart spin to the ball such that when leaving...
  46. B

    Thrust Ball bearing and Needle Bearing

    Hello all friends, My questions about the these two types of bearings. I know that what is purpose of usage. But I don't know where can I use them. If someone knows information about that, please inform me. Thanks you all.
  47. Hamiltonian

    Rolling ball inside a shell problem

    I was able to solve this problem easily by using the fact that the center of mass of the system is stationary as ##\sum F_{ext} = 0## for the ball and shell system. since COM's of both objects can be replaced with point masses at there center, the shell will have maximum displacement when its...
  48. mattlfang

    A ball hitting a two-ball system (with a spring between them)

    I honeslty don't quite know how to start. It seems like the Hooke's coefficent k is independent of the answer to this problem. I would also appreciate any clue of expressing the condition when "balls will collide again". The fact that all balls can keep moving make this rather difficult. It...
  49. M

    Rotation angle measurement of pedal with ball and socket joint

    the device that I have is the same as the mirror of this truck.
  50. O

    Law of Conservation of Energy Problem (kicking a soccer ball)

    a) So far, I have equated Ek to Eg to solve for h. 1/2(m)(27)^2 = m(9.8)h. I haven't taken the angle into consideration. I'm not sure if I have to use the x or y component. I got my answer to be 37m but again I don't believe this is correct. b) I did Ek = Eg + Ek. 1/2(m)(27)^2 = m(9.8)(3.5) +...
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