Ball Definition and 999 Threads

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. R

    How Is Torque Calculated in a Wrecking Ball Scenario?

    Homework Statement At one point during its swing, a wrecking ball exerts a tension force of 9800 N on its cable, which makes an angle of 30 degrees with the horizontal. The crane's 9 m long boom is at an angle of 55 degrees with the horizontal. What is the torque exerted by the wrecking ball on...
  2. M

    Fluids and Ping Pong Ball Magnus and Coanda Effect

    Hi PF! Given a hairdryer blowing vertically against gravity toward a ping pong ball the ping pong ball is suspended. The ball is relatively stable in the jet because the high velocity of the jet causes a decrease in pressure, causing the ambient air to mix, therefore keeping the ball in the jet...
  3. physicaled

    Circular Motion: Ball on String

    Homework Statement A 1.5 kg ball is tied to a string that is .75 m long and whirled in a verticle circle. A) Find the tension in the string at the top of the circle B) Find the tension in the string at the bottom of the circle Homework Equations Fc=mac ac= v2/r The Attempt at a Solution A)...
  4. P

    Bowling Ball rolling on a smooth floor

    Hi there! I chanced upon this problem whilst trying to brush up my Classical Mech knowledge and found it confusing. Hope someone out there can provide an insight! Homework Statement A bowling ball of mass m and radius R sits on the smooth floor of a subway car. If the car has a horizontal...
  5. D

    Thermodynamics of a cannon ball / musket ball shot bullet

    I am a computer scientist currently writing a 3D simulation for high speed projectiles both sub and supersonic for various shapes and sizes of projectiles. For now I am focused on completing simulation of a simple model of a round ball shaped projectile (ie a cannonball or musket shot). I like...
  6. E

    Ball launching off of a tray connected to a spring

    Homework Statement A 1.50-kg, horizontal, uniform tray is attached to a vertical ideal spring of force constant 185 N/m and a 275-g metal ball is in the tray. The spring is below the tray, so it can oscillate up and down. The tray is then pushed down to point A, which is 15.0 cm below the...
  7. R

    Liquid which turns into a ball?

    Is there any liquid based on viscosity and density that changes into ball. Obviously here, the liquid cannot be water. Other thing can be that some chemical is applied in hand( This doesn't make sense I think).
  8. Alanay

    Can magnets be used to send a metal ball through a pipe?

    To elaborate more on my question: Is it possible to send metal balls through a pipe with magnets arranged a certain way which could hit a target with force. I've seen something similar done before but I think the ball was also a magnet, is that the only way possible?
  9. H

    What is the deceleration of the ball?

    Homework Statement The question didn't fit there. *A boy drops a metal ball from rest on sand. It hits the sand bed in one second and makes an impression of maximum depth 8mm in the sand. What is the average deceleration of the ball as it hits the sand? Assume air resistance is negligible. vi=...
  10. S

    Rolling ball and generalized co-ordinates

    Consider a sphere constrained to roll on a rough FLAT HORIZONTAL surface. A book on classical mechanics says it requires 5 generalized co-ordinates to specify sphere's configuration: 2 for its centre of mass and 3 for its orientation. I did not understand why 3 for orientation. I guess only 2...
  11. R

    Tension in string when ball is at the top of a circle

    Homework Statement A child is swinging a .325 kg ball at the end of a .74 m long string in a vertical circle. string can withstand a tension of 12 N before breaking. What is the tension in the string when the ball is at the top of the circle if its speed at that point is 3.4 m/s? Homework...
  12. M

    MHB Yes, you are correct for both parts (A) and (B)!

    A ball is thrown straight upward. Suppose that the height of the ball at time t is h = -16t^2 + 96t, where h is in feet and t is in seconds, with t = 0 corresponding to the instant that the ball is first tossed. (A) How long does it take for the ball to drop? (B) At what time is the height...
  13. A

    Falling Feather and ball in vacuum

    I saw some of these videos showing feather and some balls falling with the same speed in vacuum. But on normal atmospheric pressure they fall depending on their weight. This is just blowing my mind, WHY is this ? Does this prove Newtons Law of Gravity is wrong ? Then how is Einstein's...
  14. EthanVandals

    Centripetal Force and Work: Understanding the Relationship

    Homework Statement A 5kg ball is swung in a circle of radius .5 meters at a constant speed of 2 meters per second, how much work does the centripetal force do as the ball does once in a circle?If the ball were pushed the same distance as the circumference of the circle with a force equivalent...
  15. N

    Algebra Kinematics: Ball above head, how fast must travel to

    Homework Statement Hello there physicsforums, I have a problem that I'd like feedback on as I'm not sure if I had solved it or approached it correctly. A ball that is traveling 5m/s is 30 meters above a person who is standing still. How fast must the person travel in order to catch the ball...
  16. R

    A ball is hit with initial velocity -- Find the Horiz/Vert displacement

    Homework Statement A softball is hit with an initial velocity of 29 m/s. at an angle of 60 degrees above the horizontal and impacts the top of the outfield fence 5s later. Assuming the initial height of the softball was .5 m above (level) ground, what are the balls horizontal and vertical...
  17. dannyboy2233

    How to analyze the compression of a clay ball

    Hello all! This is my first post on the forum. As some background, this issue pertains to the IB Physics Internal Assessment that I am in the process of writing. Thanks in advance for your help! Homework Statement My research question is: How does the drop height of a consistent-size clay ball...
  18. T

    Force generated by a solenoid on a moving steel ball bearing

    Hi, I want to find an equation for the force generated by a solenoid on a moving steel ball bearing given current, number of loops, area of the solenoid for a lab project. I've tried looking through many sources, but was unable to find anything. I also tried looking at this previous discussion...
  19. anorlunda

    Leaky Ballpoint Pens: Engineering Advancement

    I'm so old, that in 2nd grade school we still used ink wells, and ink dip pens. (And yes I did get whacked for dipping a girl's pigtail in the well.) But they were replaced by ballpoint pens, But ballpoint pens in the 50s were terrible. They leaked ink profusely. If my memory is right, leaky...
  20. FallenApple

    I How Does the Rain Frame Affect Perception of a Ball Falling Off a Cliff?

    So a ball is rolling off a cliff. The red is the proper acceleration and the blue is the geometric acceleration. How is it in the rain frame that the surface is moving down initially? Consider the situation where a rain drop falls straight down, with no ball rolling, just the ground right...
  21. M

    I Qubit mixed state density matrix coordinates on a Bloch ball

    What are the coordinates on the 3D Bloch ball of a qubit's mixed state of the form: ##\rho=p_{00}|0\rangle \langle 0|+p_{01}|0\rangle \langle 1|+p_{10}|1\rangle \langle 0|+p_{11}|1\rangle \langle 1|##
  22. T

    Conservation of angular momentum in a two ball collision

    I have two balls spinning with v1, omega1 and v2, omega2. They collide elastically with no tangential slip, resulting in new values for v1, omega1 and v2, omega2. I have the two components v1 & v2 figured out in the plane of contact, where angular momentum does not come into play. But I am still...
  23. blixel

    Class Project: Tennis Ball Launcher

    What I'm here to find out I am in the early stages of planning for a tennis ball launcher I'm doing with my group for a class project. I want to find 2 cheap electric motors that will spin fast enough, and have enough torque, so that I can attach some wheels to the spinning motors for the...
  24. S

    Projectile motion of tabletop ball?

    Hello, Could someone please check my answers to this physics problem? All my work and equations are clearly shown in the pictures below. If I got the problem wrong, please provide me with some suggestions as to how I can get it right . I'm not expecting anyone to just give me the answers :)...
  25. Andrew Bridges

    Idea for a ball point pen that makes dashed lines

    Ok. So while in my trig class, I had an idea for a ball point pen that, when writing, it has an automatic mechanism for making dashed lines. I mean to say, it lifts the ball point or obscures the path to create a perfect dashed or dotted line, or allows to draw a line of fixed length for...
  26. Markus Lervik

    Thermal velocity of a soccer ball

    Hello, I am an IB HL Physics student. I am thinking of doing my IA on the thermal velocity of a soccer ball. I will be using a soccer ball shooter (machine) to simulate the thermal velocity. I have a couple of questions: what is the thermal velocity equation, which would fit for a soccer...
  27. C

    Ball Doing a Loop Min Kin Energy: Find Angle θ

    Homework Statement A ball with radius ##r## is inside a hollow cylinder with radius ##r+R##. In the first part of the assignment, one has to calculate the minimum kinetic energy the ball has to have at the bottom in order to complete a full loop in the cylinder. It turns out to be...
  28. S

    How to calculate the mass of a ball based on a video

    Homework Statement I would like to know how I calculate mass of a ball based on a video. I can measure the speed of the ball at any point using Coach 3 (computer program). I know g=9.81m/s2 for the rest i don't know anything. I would like to know the way to calculate the mass of the ball in...
  29. Q

    Acceleration of a Ball Rolling in a Funnel

    Homework Statement A ball of mass m is given an initial velocity ⃗v and entered into a funnel. Model the acceleration of the ball over a period of time. Note: I don't have a full problem statement because this isn't really a homework question (but I figured it was homework-like enough to post...
  30. R

    Ball is thrown at the edge of the roof of a building

    Homework Statement A ball is thrown at the edge of the roof of a building in a direction at an "alpha" angle above the horizontal. It landed 5 seconds later at 50 meters from the building. The maximum height reached by the ball during its trajectory is 20 meters above the roof. Find The...
  31. Q

    Solving for Initial Velocity & Max Height of Thrown Ball

    Homework Statement A ball is thrown upwards. Its velocity at 3/5 its max height is 16.0m/s What is its initial velocity? What is its max height? Homework Equations vf^2 = vi^2 -2g(yf-yi) define up as positive The Attempt at a Solution I ran through numerous attempts on paper but can't...
  32. R

    After collision the ball comes to rest, mass of the ball is?

    Homework Statement : A stick of length L and mass M lies on a frictionless horizontal surface on which it is free to move in any way. A ball of mass m moving with speed v collides elastically with the rod at one of its extreme end( as shown in the figure). If after collision ball comes to rest...
  33. physicist007

    Will the Steel Ball's Position Change When Water is Added to the Beaker?

    Homework Statement Assume that the beaker is half filled with Hg, the steel ball being lighter will float in it half-submerged. Now we pour water into the beaker, so that the beaker is completely filled with water on top, Hg in the bottom and steel ball floating between them. Now my question...
  34. P

    A ball struck by a cue in billiards with English goes straight at first....

    Hi, let me ask probably dumb questions to physics experts... Why does the cue ball goes almost straight when its right (or left) side is struck by a cue (right English)? This is quite different from when a ball hits another ball, in which case the ball goes almost perpendicular from the contact...
  35. C

    Slipping vs No Slipping Ball Race

    The setup is a flat friction surface where the ball rolls without slipping. Next, in one case it goes up a friction incline, and in the other a frictionless incline. Which ball leaves the incline faster? Both are given the same initial push. At the bottom of the incline both balls have the same...
  36. F

    Charge on pith ball between two plates

    Homework Statement The mass of the ball is 40 milligrams, the applied potential difference is 480 V and the plate separation is 6 centimeters. If the string hangs at an angle of 20 degrees to the vertical, determine the charge on the pith ball. Homework Equations [/B] F=ma E=F/q V=E/d The...
  37. N

    How Can I Build a Golf Ball Roller Coaster with Recycled Materials?

    I have to make a roller coaster for a golf ball. It has to be made out of recycled materials. This also means no materials for construction (but chicken wire is allowed) and no prefabricated materials (Legos, Kenex, etc) 2 loops, 2 hills. Each hill has to be 20 cm height change. Can anyone...
  38. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    Homework Statement sportsman jumps at 5m/s velocity from 5m cliff to water. at what speed does he reach water? so given answer is 11.1m/s though in this book there are some wrong answers (I did try other equations and I got right answer but I want to know why I can't get it using this one)...
  39. FallenApple

    How can a ball rise higher than originally dropped?

    So here is a case where a ball is thrown on the floor with no friction. Then is a case with frictionNow what I don't understand is how is the presence of friction going to make the normal force larger than usual. The friction is dependent on the normal force, not the other way around. And the...
  40. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    Homework Statement ball dropped in air at 20m/s. why is v=20,v0=0 instead of v0=20,v=0 Homework Equations a=v-v0 / t s=x0+v0xt + at2/2 The Attempt at a Solution a=g=9.8m/s2 I know I can solve it with first finding time(I get that) a=v-v0/t making it into t=v-v0/g so 20/9.8=2.04s but now from...
  41. anon11

    Ball on a Turntable Simple Harmonic Motion

    Homework Statement A spherical ball of mass “m”, moment of inertia “I” about any axis through its center, and radius “a”, rolls without slipping and without dissipation on a horizontal turntable (of radius “r”) describe the balls motion in terms of (x,y) for a function of time. **The...
  42. R

    Dynamics: Cannon ball and the moving gun

    https://postimg.org/image/z96a0jn8b/ https://postimg.org/image/z96a0jn8b/ link to image (bcs the feature doesn't work): https://postimg.org/image/z96a0jn8b/ 1. Homework Statement A cannon (mass m_c) is standing on the ground before it fires a cannon ball (mass m_b). At the time t_0=0. the...
  43. V

    How Does Angular Velocity Affect the Ball's Position on a Basketball Hoop?

    Homework Statement A basketball player threw a ball with radius ##a## in such way that it rolls (without slipping) on a hoop of a basket with radius ##R##. Let's define an angle ##\theta## as a angle between a plane of basket and line between the point of touch of the ball and the hoop and the...
  44. S

    Calculating Torque for Ball Screws to Lift 12,000lb Transformer

    I have a set of 4 ball screws, 2 inch diameter by 0.50", one in each corner to lift up a 12,000lb transformer. Each side will have one motor driving a right angle worm gearbox in the center that will power the two other right angle gearboxes that turn the ball screws. I was given that the...
  45. G

    Projectile Motion: golf ball velocity to reach the green

    Homework Statement A golfer strikes a golf ball at an angle of 17 degrees above the horizontal. With what velocity must the ball be hit to reach the green which is a horizontal distance of 250 m from the golfer? It is at the same height as the tee. Homework Equations trig equations...
  46. doktorwho

    Calculate the maximum electrical force on a ball

    Homework Statement A metal ball of radius ##a## is at a distance ##h>>a## from a very long conducting non-charged horizontal metal surface. Calculate the maximum electrical force on a ball under the condition that ##E_{cr}## the critical electric field of air is not breached. Homework Equations...
  47. Gopal Mailpalli

    When does the ball come to rest?

    Homework Statement A ball is dropped vertically from a height H on to a plane surface and permitted to bounce repeatedly along a vertical line. After every bounce, its kinetic energy becomes a quarter of its kinetic energy before the bounce. The ball will come to rest after time? Homework...
  48. FallenApple

    Ball bounces back to same height after Angular Impulse?

    So Imagine a ball moving off a frictionless cliff with a velocity v to the right, at the bottom of the cliff the surface has friction. So after the collision, the x component of the velocity would be reduced, and the angular momentum would be fixed clockwise because the frictional impulse...
  49. anon11

    Ball Rolling Without Slipping On A Turntable

    Can someone please help me out with this tough problem? 1. Homework Statement A ball rolls on a turntable without slipping describe the balls motion in terms of (x,y) for a function of time. (The turntable spins at a constant rate) (This all the information that the professor gave us.)The...
  50. FallenApple

    Collision of Rolling Ball and Cart

    Say a ball rolls down to the right with slipping with on an arc incline so that at the bottom it leaves horizontally. The instant it leaves horizontally and is now on a cart with mass with frictional surface. So the ball will roll on the cart with kinetic friction pushing to the left altering...
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