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. I

    Ball suspended by a pulley: oscillation

    A ball of 100g, suspended from a pulley of a dynamometer, oscillates freely. The length of the pendulum thus obtained is 1m. What are the indications of the dynamometer when the ball is at the point A of it's trajectory? The maximum offset angle is 15 degrees. Homework Equations α - alpha...
  2. V

    Find the velocity when the ball rolls without slipping

    Homework Statement A thin spherical shell is sliding with velocity ##v_0## on a table initial until friction eventually causes it to roll without slipping. Find its translational velocity when the it rolls without slipping as a fraction of ##v_0##. Homework Equations $$I=\frac{2}{3}MR^2$$...
  3. T

    Integrating Gravitational Attraction in n Dimensions

    Homework Statement I'm working on a generalization of gravitation to n dimensions. I'm trying to compute gravitational attraction experienced by a point mass y due to a uniform mass distribution throughout a ball of radius a -- B(0, a). Homework Equations 3. The Attempt at a Solution [/B]...
  4. P

    Circular motion - ball in a loop

    Homework Statement This question is referring to the classic ball in a loop question where it is dropped from a height and slides into a loop de loop. Derive an expression in terms of theta the velocity of the ball at the time it loses contact with the track. Theta is measured from the...
  5. J

    Ball floating on the surface of water

    Homework Statement Homework EquationsThe Attempt at a Solution When air is evacuated , atmospheric pressure pushing down the cork is eliminated , cork should rise a little i.e option b) . This is incorrect . What am I missing ?
  6. M

    Finding acceleration from the angle made by a hanged ball.

    Homework Statement A ball with a mass of 200g, is hanged on the roof of a bus with a rope (it's mass is negligible), when the bus starts moving, the rope makes an angle of 18°. What's the acceleration of the bus? Homework Equations ΣF=m.a The Attempt at a Solution The first thing i thought of...
  7. M

    How high does the frictionless ramp have to be for the ball....

    Homework Statement What minimum height does the frictionless ramp have to be for the ball to be able to travel along the ramp into a loop upside down and not fall? Radius of loop = .3m Homework Equations PE + KE = PE + KEThe Attempt at a Solution mgh_1=mgh_2 + 1/2 mv^2 h_1 = h_2 + v^2/(2g)...
  8. doglover9754

    Throwing a ball in an airplane

    If you have seen my past thread about where a ball would end up in a car moving forward then this is kind of an extension of it. What I was wondering in that thread is where would a ball end up, being thrown straight up in a car driving forward (no windows/AC)? I thought it would land in back...
  9. sergiokapone

    Magnet's force on a metal ball

    As one know, the force on mangnetic dipole in magnetic field is $$ \vec F = (\vec p_m\cdot \nabla) \vec B_0$$, where B_0 -- external field. Let consider a some magnetic matherial with permeability \mu. The magnetization of matherial is $$M = (\mu - 1) H$$ (in SI units) and by deffinition $$M =...
  10. H

    Plasma ball electric shock mystery

    Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?
  11. Monoxdifly

    MHB [ASK] How long must he wait until the ball fall to the ground if g = 10m/s^2

    In a soccer match Putu kicked the ball with the elevation angle \alpha so that it reached the maximum height 10 m. How long must he wait until the ball fall to the ground if g = 10m/s^2? I don't know how to do it if the initial velocity isn't known. Can someone help me?
  12. Brilli

    An equilibrium problem -- Spinning a hinged rod and a ball

    Homework Statement This is a practice olympiad problem A light rod with length l is hinged in such a way that the hinge folds in one plane only. The hinge is spun with angular speed ω around a vertical axis. A small ball is fixed to the other end of the rod. (a) Find the angular speeds for...
  13. spareine

    Plasma ball, energy levels of neon and xenon

    I was wondering about the filament colors in a plasma ball that I have got. The main part of each filament is blue, but its end part is pink. Possibly the gas is 95% neon and 5% xenon, the pink part is light emitted by neon, and blue part light emitted by xenon. Using a hand spectroscope I...
  14. F

    Solving The Flight of a Ball: Examining Velocity & Time

    Homework Statement A ball is launched at 10 meters per second at an angle of 45 degrees above the horizontal. What was the duration of the ball's flight? What was it's highest point? When? What was the total distance traveled? Assume air resistance is negligible. Upwards and rightwards are...
  15. R

    How Does a Ping Pong Ball Behave in Zero Gravity?

    1. Problem Statement An astronaut is playing with a ping pong paddle and ball in zero gravity. The astronaut is 12m from a flat wall and floating toward it at 4m/s . A ping pong ball bounces back and forth between his paddle and the wall at 11m/s. Eventually, the astronaut reaches the wall and...
  16. N

    Minimum Initial Speed for Ball to Clear Hemispherical Rock

    Homework Statement A person standing at the top of a hemispherical rock of radius R kicks a ball (initially at rest on the top of the rock) to give it horizontal velocity ##v_i##. What must be its minimum initial speed if the ball is never to hit the rock after it is kicked? Homework Equations...
  17. M

    Equations to model tennis ball motion

    I'm creating a tennis game and at this point I'm trying to model ball motion. I found multiple lectures on projectiles equations of motion which seem to apply well for when ball is not moving, but they do not take into account the velocity may have at the time of impact. For example, I found a...
  18. M

    Acceleration of a golf club hitting a ball

    What will be the difference in distance of the ball if it is hit by a club traveling 120 mph at impact (constant velocity) versus a ball hit by a club traveling at 120 mph but accelerating at the point of initial impact?
  19. T

    Complete Motion of a ball in a Stable Equilibrium

    Hello Everybody! My name is TanX and I got a figure in my mind while studting concepts related to Vertical Circular Motion. I tried finding a solution to it (i.e) I tried finding the condition for movement of the particle in the figure that had come in my mind... Homework Statement So here is...
  20. S

    Ball hitting baseball bat (with no impulse)

    Homework Statement Given the setup above, what distance x should the ball be away so that there is no impulse reaction at A? Homework Equations Conservation of Linear and Angular momentum. The Attempt at a Solution Conservation of linear momentum (←+) (considering the bat alone) M(vg1) + ∑...
  21. karush

    MHB Cp2.27 How long is the ball in the air before it is caught

    $\textsf{A juggler performs in a room with a ceiling 2 m above hand level.}$ $\textit{a. what is the maximum upward speed she can give a ball }$ $\textit{without letting the ball hit the ceiling.$\displaystyle 6.26 \frac{m}{s}$}$ \begin{align*} v^2&=2(9.8)(2)\\ &=39.2\\...
  22. JTC

    Golf ball and Tennis ball turbulence

    So I have read many articles on tennis ball fuzz and golf ball dimples and I am more confused than before. Here is one that says that the dimples make the golf balls go faster: https://entertainment.howstuffworks.com/sports/golf/basics/question37.htm And just when it makes all sense, I read...
  23. F

    Coriolis effect example: ball tossing on rotating carousel

    Hi all, I was reviewing the Coriolis effect and I came across the attached explanatory image (from the Italian version of a book on physics by Cutnell, Johnson, Young and Stadler). The idea is the following. two guys are facing each other on a rotating carousel; one of the guys on the throws...
  24. Glurth

    Can a Self-Gravitating Gas Ball Simulate Stellar Formation Dynamics?

    I have a simulation I'm trying out (for fun). A self-gravitating ball of gas, in deep space. (The sim uses a fixed-time-step for each iteration.) I'd like to use Boyles Ideal gas law, the force of gravity, and energy as internal heat. (I don't want to touch enthalpy unless I don't realize...
  25. HappyFlower

    Finding the Speed of a head hit by a soccer ball

    Homework Statement When a soccer ball is kicked toward a player and the player deflects the ball by "heading" it, the acceleration of the head during the collision can be significant. Figure 2-38 gives the measured acceleration a(t) of a soccer player's head for a bare head and a helmeted head...
  26. T

    Measuring one second with a bouncing ball

    Hello Theoretically any ball that bounces 1.225 metres high is in the air for one second. This is fairly precise, +/-4% time variance is +/- 10 cm height variance, so bouncing to a height of 1.13 metres is 0.96 seconds and to a height of 1.32 is 1.04 seconds. The theory is at least dependent...
  27. talknerdy2me

    A ball moves a horizontal circle....

    Homework Statement While a string is attached to a ball and the ball moves in a horizontal circle at a constant speed, does the force change both the direction and speed of the ball? Explain. Homework Equations No equations necessary. The Attempt at a Solution *I think* the force changes...
  28. G

    What is the Velocity of the Ball After Impact?

    Homework Statement Instead of using a ballistic pendulum, a bullet with velocity u is fired at a stationary solid ball resting on a surface. If the bullet deflects at an angle of 30◦ to its original path and the ball is nine times more massive than the bullet, what is the velocity of the ball...
  29. doglover9754

    What in gravity makes water on Earth into a ball?

    So, from my last thread “Why doesn’t the water fall out of the Earth?” I asked if the reason why water doesn’t fall out of the Earth even on its tilted axis. Then the conclusion was gravity. To be more precise, gravity is the one that pulled the water on Earth into a ball form. What in gravity...
  30. Alexanddros81

    A ball is placed on the spring and launched vertically, Find k

    Homework Statement 14.28 The spring of stiffness k is undeformed in the position shown. The 30-g ball is placed on the spring and launched vertically by compressing the spring 150mm and releasing it. If the ball reaches an elevation of 14.25m above A, determine the value of k. Homework...
  31. B

    Initial velocity of ball B hit a free falling ball A

    Homework Statement A boy release ball A from height 5m from ground at the same time other boy throw ball B vertically upward to exactly strike ball A. When ball B released it was 1m from ground find minimum initial velocity of ball b. Given g=10m/s^2 a) 2m/s b) 3m/s c) 4m/s d) 5m/s Homework...
  32. scott ketter

    What is the final velocity of a ball rolling through a tube?

    I am making a physics simulator and this problem is tricky. You have two freely moving objects with known masses and velocities in a frictionless environment. The first object is a ball and the second is a pipe. They are moving toward each other. I need to know what formulas are used to simulate...
  33. T

    Collision of a billiard ball against a wall

    The collision of a billiard ball against a wall is considered elastic. Intuitively i can accept it. But analytically i don't understand it. Why does the wall not take any relevant amount of energy from the ball? Is it connected to the change in temperature of the wall ? What scenarios can we...
  34. F

    Collision of a ball with a rod on a track

    The rod is attached and can frictionlessly slide on the purple track. The questioner specified that the collision is elastic. The first obvious error in this problem is that the direction and magnitude of the final velocity of the ball is impossible. If the ball carries off all the energy it...
  35. K

    Circular motion, string and ball in a horizontal circle

    A mass m = 0.15 kg is attached to a massless string and rotates at constant speed v = 4 m/s in a horizontal circle of radius 2 m. The tension T (in N) in the string is: (a) 1.1 (b) 1.9 (c) 2.4 (d) 3.3 (e) 4.9 I would assume that first I calculate the centripetal acceleration by using v^2/r =...
  36. F

    Ball rolling down an incline angular and linear acceleration

    Homework Statement A ball with moment of intertia bmr^2 rolls without slipping down a plane inclined at angle O. What is it’s linear acceleration? Homework Equations Fnet= ma T = F x r T = IO’’ a = rO’’ The Attempt at a Solution Fnet = mgcos(O) - FfT = FfrT = IO’’ Ffr = bmr^2O’’ Ff =...
  37. E

    Rod swinging and hitting a ball

    Homework Statement There is a uniform rod of mass m = 1 kg and length L = 0.2 m fixed to the wall by an axis passing through its end. A uniform ball of mass M = 0.1 kg and radius R = 2.85 cm is on the ground, below the axis of the rod, such that the rod's unfixed end is at the height of the...
  38. D

    How to mark a "measles ball" for practicing Snooker spin

    Please excuse me if it's not appropriate to post this question here, but since this group has knowledge of both math and snooker... I'm wanting to make my own "measles ball" for practicing spin on the cue ball. These are cue balls with 6 dots perfectly/evenly spaced on the ball so you can see...
  39. ferrariistheking

    Work, energy, power tennis ball problem

    Homework Statement A force applied to a tennis ball is described by the function F(x) = 2x + 5, with the force in Newtons and the position in meters. How much work does the force do on a tennis ball as it moves from -2.5 m to a new position of 2.4 m? Homework Equations F(x)= 2x+5 force x...
  40. E

    A tennis ball bounces off a wall....

    Homework Statement A 60 g tennis ball with an initial speed of 37m/s hits a wall and rebounds with the same speed. This collision lasts for two seconds. What is the maximum value of contact force during the collision? Homework Equations p=mv The Attempt at a Solution So I multiplied the mass...
  41. G

    Force Questions -- Snooker ball collision and a rock through a window

    Homework Statement These are two conceptual questions we were given recently. It's strange how mathematically I regularly do much harder problems but these caught me out a bit Q1. If a one snooker ball hits another ball moving at constant speed, why does the second ball move? Surely due to...
  42. VSayantan

    Elastic Collision between a Ball and a Stick

    Homework Statement [/B] A mass ##m## travels in a straight line with velocity ##v_0## perpendicular to a uniform stick of mass ##m## and length ##l##, which is initially at rest.. The distance from the center of mass of the stick to the path of the traveling mass is ##h##. Now the traveling...
  43. Pushoam

    No. of trials for P>0.99 of at least one basket ball success

    Homework Statement Homework EquationsThe Attempt at a Solution Probability of getting no success in one trial ##P( \bar p) = 1 – P (p) = 0.25 ## Probability of getting no success in n trials ##P_n( \bar p) = (1 – P (p) )^n= (0.25)^n ## Probability of getting one success in n...
  44. V

    Potential energy of a ball on top of a vertical rod

    Homework Statement The problem is to take a small ball of mass m on a uniform rod of mass m which is hung on a hinge vertically downward, they're asking to find the velocity to be imparted for it undergo a complete rotation. I have the kinetic energy bit worked out but I'm getting the wrong...
  45. C

    The equation to find the frequency of a bouncing ball

    [Mentors' note: No template because this thread was moved from the General Physics forum] Ok so first of all believe me i would not make a new post if i found the answer anywhere online but i i couldn't find it. Right now i am doing an experiment to find the frequency of a bouncing ping-pong...
  46. ubergewehr273

    Problem about an elastic collision between a rod and a ball at an angle

    Homework Statement Homework Equations Conservation of linear momentum Conservation of angular momentum ##\frac{-v_{relative after collision}} {v_{relative before collision}}=e## where e is coefficient of restitution The Attempt at a Solution Components of velocity given as...
  47. S

    Angular Momentum of a Ball at Half Height

    Homework Statement In the figure, a 0.400 kg ball is shot directly upward at initial speed 58.3 m/s. What is its angular momentum about P, 1.42 m horizontally from the launch point, when the ball is (a) at maximum height and (b) halfway back to the ground? What is the torque on the ball about P...
  48. J

    How Does a Dog Running on a Ball Affect Its Motion on an Inclined Plane?

    <Moderator's note: Moved from a technical forum and thus no template.> We place a ball on an an inclined plane (angle ##\theta##). At the top of the ball is a small dog who always stays at the top over the course of the ball's movement. What is the motion of the ball? ------------------ I...
  49. D

    Kinematics Involving Ball, What did I do wrong?

    Homework Statement Your cousin has built a model rocket that she wishes to launch in your backyard. You're a little worried by this, and ask her for details. She tells you, when I launch the rocket straight upwards, the acceleration will be 3.5g = (3.5*9.8m/s^2) for 4.3 seconds, then burn out...
  50. astrocytosis

    Ball rolls without slipping in an accelerating car

    Homework Statement A bowling ball sits on the smooth floor of a subway car. If the car has a horizontal acceleration a, what is the acceleration of the ball? Assume that the ball rolls without slipping. Homework Equations torque = R x F = Iα aball= Rα Isphere = (2/5) MR2 The Attempt at a...
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