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. P

    Gravitational force for a ball and particle

    Homework Statement How far from a very small 110kg ball would a particle have to be placed so that the ball pulled on the particle just as hard as the Earth does? Homework Equations Fg= gMm/r^2 The Attempt at a Solution I used the equation and plugged in the numbers for the ball...
  2. M

    Inelastic collision between ball and rotating system.

    Homework Statement A homogenous, thin stick with the mass m and the length l is hanging from the ceiling and can rotate freely around the point P. A small ball with the mass of M is attached to the end of the stick. The small ball on the end of the stick gets hit by another small ball with...
  3. P

    Rolling a ball off a roof (ramp)

    Homework Statement In this problem, I'm rolling a ball off a ramp. The ramp is supposed to simulate a roof. The hypotenuse of the ramp is 1.5 meters and the angle is 45 degrees. The distance from the edge of the ramp to the ground is -5.43 meters. That is the information I'm given. From there...
  4. M

    Ball attached to string attached to wall, find force against wall

    Homework Statement A solid uniform 50kg ball of diameter 30cm is supported against a vertical frictionless wall using a thin 35cm wire of negligible mass (the wire is attached to the wall, the ball is attached to the wire and rests against the wall). Make a free body diagram for the ball and...
  5. D

    MHB Surface Area of ball floating in water

    Using calculus, how would I derive a formula for the exposed surface area of a ball floating in water? For such a formula to be a good candidate, it would have to consider oscillations of the water and placid water. The surface area of a sphere is \(A = 4\pi r^2\).
  6. E

    How Do You Calculate the Initial Velocity and Range of a Soccer Ball?

    Homework Statement A person kicks a soccer ball with an intial velocity directed 53 degrees above the horizontal. The ball lands on a roof 7.2 m high. The wall of the building is 25m away, and it takes the ball 2.1 seconds to pass directly over the wall. Calculate the intial velocity of the...
  7. samjohnny

    Is Quantum Behavior Observable in a Tennis Ball?

    Homework Statement Attached. The Attempt at a Solution I've attached it. I'm not sure if I've gone wrong somewhere; I've got an extremely high quantum number, but I guess that should be expected considering we're dealing with macroscopic objects. Could someone kindly check to see if...
  8. Saitama

    Friction and Energy Conservation in Ball Colliding with Wall

    Homework Statement Homework Equations The Attempt at a Solution I have dealt with the case when the wall is frictionless and the rolling ball collide with it but I am not sure how to proceed here. When the ball comes in contact with the wall, the friction due to wall acts in the vertically...
  9. M

    Bouncing Ball and the Principle of Equal and Opposite Forces

    Homework Statement A ball hits the wall.So wall will exert an equal and opposite force the ball Why doesn't the ball's forces gets equal so it moves with constant velocity? Homework Equations Gui Na The Attempt at a Solution No attempt needed here.F-F=0 net force.
  10. G

    Rubber ball colliding with steel ball of equal mass

    Homework Statement Suppose a rubber ball collides head-on with a steel ball of equal mass traveling in the opposite direction with equal speed. Which ball, if either, receives the larger impulse? Explain. Homework Equations p = m*v impulse force = change in p The Attempt at a...
  11. S

    Proving Open Sets and Open Balls in Normed Spaces

    Homework Statement Show that S is open if and only if ∀x ∈ S, ∃ a open ball B(x; r)(r > 0) such that B(x; r) ⊂ S And what we have is , let X be normed space, S ⊂X , Then S is close if and only if $$∀{x_{n}}⊂X, s.t. x_{n}->x \in X$$, x∈ S. A set S is open if and only if X\S is close...
  12. G

    Electric Potential inbetween Conducting Metal Ball and Thick Shell

    Homework Statement A conducting metal ball of radius 2m with a charge of 3μC is surrounded by a concentric spherical shell of inner radius 4m and outer radius of 5m with a total charge of 4μC. Determine the electric potential in volts between the ball and shell at a radius of 3m...
  13. S

    Ball valve plugging with solids, alternatives ideas to fix problem?

    I am having issues with solids building up in the 10” discharge ball valves on Mother Liquor Pumps that prevent operations from being able to close the valve. I have had a few discussions regarding ways to improve or eliminate this issue which have included insuring the valve is insulated/traced...
  14. C

    How does external work affect the height of a bowling ball when pushed?

    Ok so when one drops a bowling ball hanging from a rope, it won't come back and smack him in the face. This I can understand, due to potential energy of gravity and conservation of energy. However when someone pushes the bowling ball, how can you show that it will rise higher than the original...
  15. B

    Calculating Ball Speed for Vertical Ascent

    Homework Statement With what speed (in feet/second) must a ball be thrown vertically upward in order to rise to a height of 85.0 ft, neglecting air resistance? Homework Equations g=9.8 m/(s^2) speed=distance/Δt The Attempt at a Solution I started off by setting speed=85.0ft/Δt I...
  16. gcombina

    Conservation of Momentum of a snow ball

    A 35-kg girl is standing near and to the left of a 43-kg boy on the frictionless surface of a frozen pond. The boy tosses a 0.75 kg ice ball to the girl with a horizontal speed of 6.2 m/s. What are the velocities of the boy and the girl immediately after the girl catches the ball? I don't know...
  17. A

    Height when a ball is thrown vertically at half its velocity

    Homework Statement A baseball is thrown vertically into the air with a velocity, v, and reaches a maximum height, h. At what height was the baseball with one-half its original velocity? Assume no air resistance. Homework Equations v22 = v12 + 2ad ? The Attempt at a Solution let...
  18. O

    Drop a ball - where does the energy go?

    Hi - If I lift a bowling ball in the air, so that it has potential energy, then drop it on the dirt, it makes a sound and a dent. Where did all the energy go? It did not all go to sound, since there's a dent, right? A small bit went to heat... what else? Thanks
  19. B

    Find angle with pith ball and vertical wall

    1. The Question: A 10.0 g pith ball, carrying a charge of 1.52 μC hangs from a thread attached to a charged vertical wall carrying a surface charge density σ = 3.57 μC/m2. Find the angle that the thread makes with the vertical. Homework Equations [b]3. My attempt: Tcosθ=mg...
  20. W

    How can we accurately calculate the time of impact in a real-life collision?

    In an inelastic collision of a moving billiard ball with a second ball at rest, I understand that the two balls have the same velocity after contact, correct? But at the instant of contact how do the velocites of the two balls change instantaneously? Doesn’t that imply an infinite force...
  21. A

    Projectile motion cannon ball angle

    I need a bit of help with this simple question, it's not difficult at all but I just can't see what I did wrong. I'm overlooking a crucial thing A cannon is placed 40m away from a 37.5m high cliff. The cannon fires a ball with an angle of 45 degrees to the horizontal. The gravitational...
  22. N

    How far can a golf ball travel on the moon?

    Homework Statement If you can hit a golf ball 180m on Earth, how far can you hit it on the Moon?The Attempt at a Solution Since this question deals with range; sx = [vxi^2 sinΘ]/g My problem is that I do not have the velocity at which the golf ball is being hit. As for the launch angle, I...
  23. I

    Ball thrown up, find max height - Given one velocity in midflight

    Homework Statement A ball is thrown upwards from a point near the sidewalk next to a tall office building. At some later time an occupant of the building, exactly 5.1 meters above the point from which the ball was released, sees it pass her window with a speed of 2.9 m/s. Calculate the...
  24. P

    Ball performing small oscillations within a hollow cylinder

    Homework Statement A small ball of radius r performes small oscillations within a hollow cylinder of radius R. What would be the angular frequency of the oscillations given that the rolling is without slipping? The angle between the radius connecting the center of the hollow cylinder to the...
  25. C

    Why Does My Ball Trajectory Simulation Show Only Positive Vertical Velocities?

    I am attempting to create a spreadsheet that models the flight path of a sphere. My model should consider air resistance, but I've opted to ignore magnum. As a resource to help me, I'm using http://www.team2834.com/team_documents/Projectile_motion_with_air_resistance.pdf, but I have ran into...
  26. STEMucator

    Calculating Initial Velocity in Elastic Collision of Two Balls on a String

    Homework Statement A ##0.02kg## ball is fired horizontally with a speed ##v_0## towards a ##0.1kg## ball hanging motionless from a ##1.0m## long string. The balls undergo a head-on, perfectly elastic collision, after which the ##0.1kg## ball swings out to a maximum angle ##\theta = 50°##...
  27. C

    Special Relativity, Train, Ball

    Homework Statement A train with proper length L moves at speed 5c/13 with respect to the ground. A ball is thrown from the back of the train to the front. The speed of the ball with respect to the train is c/3. As viewed by someone on the ground, how much time does the ball spend in the air...
  28. S

    Projectile motion of tennis ball with air resistance

    Hi, so I am trying to model the path of a tennis ball when serving. I already have the model without air resistance, but now I'm getting into differential equations with the air resistance. I obtained two differential equations for acceleration that i think are correct, but I'm not sure where to...
  29. F

    Rolling Ball and angle of incline

    Homework Statement A uniform solid sphere rolls down an incline without slipping. If the linear acceleration of the centre of mass of the sphere is 0.2g, then what is the angle the incline makes with the horizontal? Repeat for a thin spherical shell. Homework Equations \sum \tau = I \alpha...
  30. A

    What is the Correct Height to Hit a Billiard Ball for Rolling Without Slipping?

    Homework Statement This problem has already been discussed in lots of places through internet but none of them seems to be the correct answer in my opinion. So i tried to solve it and i'd like you to check my reasoning. So the problem is: If a billiard ball is hit in just the right way...
  31. D

    Floating Hollow Ball: Defying Balloon-Like Properties

    Is there any material,when made a hollow ball out of it & filled with lighter gas than air,will rise in air according to archimedes principle? But upon removal of that gas,it should not contract itself in volume like any balloon does...it should be able to retain its volume as it is even if...
  32. M

    How Much Does the Spring Compress When Hit by a Rolling Ball?

    Homework Statement A problem like this is on my final tomorrow and I can't seem to get past part C...Please Help! A .321 kg, .27m radius thin shelled ball rolls (starting at rest) 3.82m from the top down a 35° 10.0m long incline without slipping. After the 3.82 m, the incline becomes...
  33. D

    Accelerate a ball bearing through a 90 degree turn

    I am looking to accelerate a ball bearing through a 90 degree turn using an impulse from an electromagnet wrapped around a bent tube. What I want to know is what is the minimum radius turn you could use, obviously if the radius of the turn is too small the ball will simply impact the wall at the...
  34. N

    How Do You Calculate the Initial Speed to Throw a Ball Downward from a Building?

    Homework Statement You're atop a building of height, h, and a friend is poised to drop a ball from a window at h/2. Find an expression for the speed at which you should simultaneously throw a ball downward, so the two hit the ground at the same time. Homework Equations None The Attempt at a...
  35. S

    Collision of ball with inclined plane

    1. Hi, I'm a computer engineering graduate. I'm developing a computer game similar to Soundrop (Apple). The situation is: balls fall vertically down under the effect of gravity. There are various inclined planes in the frame (of known angle of inclination). There could be multiple...
  36. NATURE.M

    Angular Momentum of a ball of clay

    1. Homework Statement [/b] Consider a thin rod of mass m_{r} and length L hanging from a pivot at its upper end. A ball of clay of mass m_{c} and of horizontal velocity v_{0} strikes the lower end of the rod at a right angle and sticks, causing the rod + ball to rotate. What is the angular...
  37. V

    Rotating ball and string Rotational Kinetic Energy?

    Homework Statement Hello, I am a bit confused on when rotational kinetic energy exists and when linear kinetic energy exists. For example when we spin a string with a ball attached to the end it has kinetic energy of 0.5mv^2 of the ball when we were solving for velocity of the ball at certain...
  38. M

    Impulse and Average Force. Ball by the Wall.

    Homework Statement A ball of mass m= .25kg is moving with an initial velocity of \vec{v}=(8.0\hat{x}+8.0\hat{y})(m/s). It rebounds from a wall and has a final velocity (after impact) of \vec{v}= (-5.0\hat{x}+6.0\hat{y})(m/s) a.) Determine the impulse exerted on the ball by the wall...
  39. Patolord

    Maximum Velocity of a Falling Ball on a Spring

    Homework Statement A sphere of 4kg falls from a height of 70cm and lands on a spring of constant 2 *10² N/m. Whats the max velocity the sphere reachs? g=10m/s²Homework Equations Ep=m*G*h Ek=mv²/2 Eel=k*x²/2 Vmax=sqrt(2g*h) (internet source idk if this is right)The Attempt at a Solution I tried...
  40. M

    Engineering Statics 3D equilibrium (sleeves and ball joints)

    Homework Statement Ends A and B of the 5-kg rigid bar are attached by lightweight collars that may slide over the smooth fixed rods shown in the figure. The center of mass of the bar is at its midpoint. The length of the bar is 1.5 m. Determine the horizontal force F applied to...
  41. P

    Velocity of ball after being hit by a racket

    I'm trying to figure the velocity (and specifically the angle) of a squash ball (for example) after being hit by a racket. Simple case: say the ball is initially stationary (hanging in the air!) and the racket hits the ball "flat". That is the velocity of the racket it normal (perpendicular)...
  42. Milsomonk

    A ball rolling down a slope, find its velocity.

    Hi guy's, I've got an interesting problem in my coursework, I have to say I am stumped, so here it is. A hollow sphere of mass 56 grams, starts at rest and is allowed to roll without slipping 2 metres down a slope at an angle of 25 degrees. Gravity is assumed as 10 ms^2. clculate the velocity...
  43. S

    Ball throwing model and some questions about QED

    I read recently in my old ugrad 2012 solid state physics textbook, in its discussion of the attractive force between electrons in cooper pairs (in superconductors), that the attractive force between cooper pairs is explained mostly by the exchange of phonons (a quasiparticle associated with the...
  44. C

    Finding Friction in Equilibrium Rod on Ball

    Hi guys. I have one problem from competition that I can't solve. I'll try to translate it. "rod of mass m and length l is lying on a ball of radius R in state of equilibrium. The rod makes angle θ with the horizontal. There is friction in every point of contact, and it's assumed that it is...
  45. M

    What factors affect the movement of a ball bearing attached to a spinning disc?

    Hello everyone, Being new here, and not a "Physics Guy" I wasn't sure where this should go, but General Physics seemed like the best bet. Recently I've been thinking about the effects of circular motion on external objects, and I've hit dead end with one of my trains of thought. Excuse...
  46. M

    Calculating the Final Velocity of a Thrown Ball

    Homework Statement A boy throws a baseball directly upward. He catches it 3.2 seconds later. Homework Equations a=Δv/Δt The Attempt at a Solution Letting up be positive, I think the acceleration would be positive 9.8 m/s^2. I think I am trying to find the final velocity. I think that the...
  47. S

    Angular Momentum of a rotating ball

    Homework Statement What is the angular momentum of a 0.210-kg ball rotating on the end of a thin string in a circle of radius 1.35m at an angular speed of 10.4 rad/s? Homework Equations I am using L = Iω The Attempt at a Solution I put I = (2/5)(0.210 kg)(1.35m)^2 ω = 10.4 rad /...
  48. K

    Equation for Ball Deflection at Corners in a Breakout Game

    Hi First Post so go easy. I am teaching a programming course for kids between 10-14. We are using scratch which is a sprite animator. We are trying to make a breakout game (you know the one where you break block with a ball) We have a ball sprite that we can easily bounce around the...
  49. Y

    Question on Laplace eq. in a ball

    For ##\nabla^2 u(r,\theta, \phi)=0##, ##u(r,\theta, \phi)=r^{n}Y_{nm}(\theta,\phi)##. But I have issue with this, for spherical coordinates: \nabla^2u=\frac{\partial^2{u}}{\partial {r}^{2}}+\frac{2}{r}\frac{\partial{u}}{\partial {r}}+\frac {1}{r^{2}}\left(\frac{\partial^2{u}}{\partial...
  50. L

    Compactness of a Closed Ball in C([0,1])

    Homework Statement Show that the closed ball in ##C([0,1])## of center ##0## and radius ##1## is not compact.2. The attempt at a solution I was given a hint, to look at the sequence of continuous functions ##f_n(x) = x^n## on the closed ball in ##C([0,1])##. Why is that sequence continuous...
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