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. M

    Forces acting when we squeeze a ball?

    I have few doubts to clear. I would like to know the forces acting when we squeeze a foam ball. Mode of squeeze will be by placing the ball between the palm of the hand and the four fingers. What will be the force acting at the center of the ball when we squeeze? Is the force same through out...
  2. P

    How Far Will the Ball Roll Relative to the Ground in 0.10 Seconds?

    Homework Statement I am a substitute today for a physics class. I am baffled by the following and could use some help. A 0.50 kg ball sits on a cart. When the cart is pulled to the right by a net force of 3N, friction exerts a force of 2.0 N on the bottom of the ball. The ball rolls without...
  3. E

    Modeling Ball and Spinning System

    How should I go about modelling a ball and spinning beam system in matlab? It's similar to the ball and beam control system except the beam spins like a propeller so the control system has to account for the centripetal force. Any reference papers?
  4. E

    Rotational motion -- Ball rolling back and forth on a U-shaped ramp

    If a ball rolls down a U-shaped ramp from a height h, why does it not reach a height h on the other side? (Frictionless ramp) It will reach a height of (5/7)*h, but I'm not sure why. Some of the potential energy is converted to rotational and some is translational kinetic, but why do they not...
  5. S

    Two people in a boat and one person throws a ball

    1. Two people sit at opposite ends of a boat. Ther person at the front of the boat has a ball and throws it to the person sitting at the back of the boat who catches it. What is the motion of the boat at the time immediaately after the ball is thrown and later after the ball is caught ? Answer...
  6. M

    How to predict how far a spinning ball will bounce?

    Homework Statement If I were to drop a spinning ball vertically, the spin would cause the ball to bounce a certain horizontal difference. Intuitively, the rougher the surface it bounces against, the further the ball should bounce. How would you quantify this relationship? Homework EquationsThe...
  7. madmike159

    How Do You Solve a Suvat Problem for a Ball Thrown Off a Roof?

    Homework Statement A ball is thrown vertically upwards from a roof of a building and it lands 3 seconds later on the ground 7 meters below the roof. Calculate: a) the speed with which the ball was thrown upwards b) the maximum height of the ball above the ground c) the speed with which the ball...
  8. M

    Small question about speed of the ball

    Homework Statement Hello everyone, I have this very quick and simple question: This is the drawing of the problem and I have to find the speed of the ball. Homework EquationsThe Attempt at a Solution I found ac to be 0.83m/s2 and R = 1.2855 do I simply use this formula to find the speed...
  9. gracy

    Final velocity in SUVAT equations -- ball thrown from a wall

    Homework Statement :[/B]There is a wall of height 30 meters.From the top edge of the wall a ball is thrown up with a velocity of 5m/s.Find the time taken by the ball to come to the base of the wall. Take g=10 m/s^2 Homework Equations :I used V=u+at[/B]The Attempt at a Solution v=0 as ball will...
  10. N

    Matlab Simulink: Simulate the height of ball thrown upward

    Homework Statement Upthrow simulation Conditions: initial velocity v=10m/s, initial height h=0m when t=0. Gravity acceleration g=10m/s2 . Using Simulink to simulate the variation of height with time when t≥0. Homework Equations I figured that the governing equation should be: Height =...
  11. L

    Kinetic energy of Earth and ball system

    Homework Statement There is a system consists of a ball and the earth. Explain why you can consider the kinetic energy of the system equals to the kinetic energy of the ball. Homework Equations ##F=-\frac{m_{1}m_{2}}{{r}^{2}}## The Attempt at a Solution The magnitude of the force acting on...
  12. J

    Ball thrown off the top of a hill, ball hits hill

    Homework Statement Alice and Bob are having a competition to see who can throw a baseball the farthest from the top of a hill which slopes downward uniformly at an angle ϕ. Alice plays softball, and Bob doesn't have a particularly good arm, so he knows that he's probably going to lose...
  13. W

    A ball of mass m is thrown with a velocity v at a disk

    Homework Statement A ball of mass m is thrown with a velocity v at a disk of mass M which sticks to the rim on impact.https://s3.lite.msu.edu/res/msu/perl_author/P3_PRELECTURE/L_CONSERVATION/IMAGES/CQ1.png For the system of the ball and disk, what is the total initial angular momentum about...
  14. J

    Determine the horizontal distance that the ball traveled

    My teacher never taught us any of this. She just gave us a worksheet, and told us to solve it. I need to know how to solve this for a quiz tomorrow. Problem: Matt hits a baseball with an initial speed of 125 feet per second at an angle of 40 degrees to the horizontal. The ball was hit at a...
  15. Y

    Ball roll down from the top of a rough spherical dome

    Homework Statement A ball is rolling down from the top of a rough spherical dome with negligible initial velocity and angular velocity. Show that the ball must slide before losing the contact with the dome. Homework Equations ΣF=ma Στ = Fr = Iα fs = μsN vcm = rω Δmgh = 0.5mvcm2 + 0.5Icmω2 I =...
  16. T

    Ball rolling on a larger ball on a surface

    I've just been wondering about this kind of problem. Let m be the mass of the smaller ball, and M be the mass of the larger ball. Assuming the ball does not slip and that the surfaces are frictionless, what is the time that it takes for the smaller ball to reach the bottom/floor if the the radii...
  17. kingsmaug

    How Long Does It Take for a Bowling Ball to Stop Sliding and Start Rolling?

    Homework Statement A spherical bowling ball with mass m = 4.3 kg and radius R = 0.102 m is thrown down the lane with an initial speed of v = 8.2 m/s. The coefficient of kinetic friction between the sliding ball and the ground is μ = 0.29. Once the ball begins to roll without slipping it moves...
  18. C

    Ping-Pong Ball Submerged in Water and then Released

    Homework Statement Direct problem statement: Imagine you are playing with a Ping-Pong ball in a swimming pool. You push the ball down to a depth of 1 m below the surface, then release it. How high above the water surface will the ball shoot as it emerges from the water? Assume the ball has a...
  19. L

    Why do moving balls and bicycles eventually come to a stop?

    Hello, members. Why does a moving ball stop and why does a bicycle stop when cyclist stops pedaling? What's the physics behind it? Kindly explain your answer. Thank you.
  20. nuuskur

    Proof: open ball is an open set

    Homework Statement Second try at the proof, this time with correct vocabulary, I hope Prove that an open ball is an open set. Homework EquationsThe Attempt at a Solution Let B(P_0, r) be an open ball in \mathbb{R}^m, where P_0 is the centerpoint of the ball and r > 0 is its radius. Assume...
  21. A

    How does the placement of sensors affect stress in a squeeze ball?

    Hi, I have two squeeze balls with pressure sensors inside them. One squeeze ball(Ball A) has a sensor placed at the center while the other one(Ball B) has two sensors, placed very close to the two opposite surfaces. These squeeze balls act as an input to a game developed. Depending upon the...
  22. T

    Why is a metallic ball attracted to an electromagnet?

    I always heard that magnetic forces don't do work, and that they act perpendicularly to the direction of movement.
  23. L

    Calculating the Impulse of a dropped ball

    I would like to start off by excusing myself in advance for not knowing all of the correct terminology, since I am not studying physics in English. 1. Homework Statement A ball is dropped from a certain height, it then falls down towards the ground and consequently bounces up again to a...
  24. B

    Normal-Tangential Coordinate for Ball Moving in Circle

    Homework Statement The problem is: The ball B is traveling on a horizontal circle table. It is attached to the string that leads through a hole in the center of the circle. At the very beginning, the ball B is traveling around a circular path counter-clockwise, then the cord is pulled down...
  25. lasisdabomb

    A Child throws a ball vertically upwards, then catches it

    Homework Statement Taking the intial velocity to be 10.0 m/s, g to be 9.8m/s2 and ignoring effects of air calculate: -the total time of flight of the ball -the maximum height it reaches variables: u=10 a=9.8 Homework Equations v=u+at x=vt-1/2at The Attempt at a Solution I've recently...
  26. Y

    Center of Mass for a Bowling Ball

    Hey everyone! I recently worked through finding the moment of inertia of a cylinder with a cylindrical cavity off center, and I wish to further deepen my understanding of calculating the center of mass of such objects. So I made up the following problem: Homework Statement Find the center of...
  27. G

    Ball Bearing Selection for Wheel Hubs

    Hello there guys I'm trying to find out which ball bearings I have to use for a new wheel hub I am designing. What I'm currently doing is a load analysis for the axis but I am confused on how would the forces that affect the wheel (normal, friction, lateral force when the car takes a turn...
  28. Serious Max

    What times it takes for the ball to drop?

    Homework Statement When you drop an object from a certain height, it takes time T to reach the ground with no air resistance. If you dropped it from three times that height, how long (in terms of T) would it take to reach the ground? Homework Equations ##x=x_0+v_{0x}t+\frac{1}{2}a_x t^2## The...
  29. P

    Calculating Velocity of Ice Skater After Throwing Snowball

    Homework Statement A 63 kg ice skater, at rest on frictionless ice, tosses a 4.06 kg snowball with velocity given by v = ( -14.3 i + 17.2 j ) m/s, where the x and y axes are both in the horizontal plane. Find the subsequent velocity of the skater. Homework Equations p = mv p = m1v1+... The...
  30. S

    Is the ball's height the same on Earth and Mars?

    Hi, I understand that if a ball is dropped on Earth and dropped on mars, the ball will reach the same height on both planets thanks the law of conservation of energy. Can anyone prove this mathematically? Thanks in advance
  31. J

    Projectile motion basketball ball shot help

    Homework Statement So I am given the height of a basketball player (2.00m tall) and the height of a basketball net (3.05m tall) and the distance at which the player stands from the net (10.0m away). The player shoots the ball at an angle of 45.0 degrees. What must the initial velocity be to...
  32. M

    Calculation to launch a golf ball

    Hi, I need your help. Is my calculation correct? 1. Homework Statement We have to build a launcher that will be able to reach a target that is place anywhere in a prism 3m X 3m X 1m. The launcher have to used a golf ball and gravity as source of energy. I am trying to calculate what we need...
  33. H

    Torque: stick resting on a bowling ball

    Homework Statement http://imgur.com/d0kW2Kr Homework Equations Net torque = 0 The Attempt at a Solution The work is done in the image. I only included the forces that were relevant to the answer. The answer is N = 0.983 Newtons. I have a feeling that my incorrect answer is due to the...
  34. V

    Momentum is not conserved with elastic bouncing ball?

    So if you throw an elastic bouncy ball at the non-closed door, it will bounce off with bigger velocity than it was approaching the door before hitting it, as well as the door will now have some gained momentum and will move. P (momentum) = mv In this case, it appears as if the ball gained...
  35. rcgldr

    Explanation for ball hovering in a vertical stream

    Example video I made a few years go: Note that most of the air interacting with the ball flows around the ball, as demonstrated near the end of the video where a tube is used to prevent flow around the ball, causing the ball to shoot upwards. The main point of this post is the explanation...
  36. V

    Gravity/density equation? Giant ball of water

    Can you help me find the equation for determining density when also taking the object's own center of gravity into account? For example, say I have an Earth-sized volume of water (or pick any simple spherical object). You have to account for the increase of density as you go closer to the center...
  37. D

    Kinematics Question -- A soccer ball bounces off a wall

    Homework Statement "A person kicks a soccer ball at an angle 30° above the horizontal on the ground. The ball then hits a wall at an angle 15° below the horizontal 4.9 seconds later. Determine the height at which the ball hit the wall." (Assume acceleration due to gravity is 9.80m/s2 [Down].)...
  38. A

    What are the forces acting while squeezing a ball?

    Hi, I am new to this forum. I am currently working on a project in the field of tangible user interface. I am developing a game in which a pressure sensor squeezable ball is the input controller. I am done with the game. Now I need to design a squeeze ball. My next aim is to find out the...
  39. goonking

    Velocity vs Time: Dropped Ball Analysis

    Homework Statement http://imgur.com/FJzyuSY Homework EquationsThe Attempt at a Solution since the graph is velocity and time, i believe the slope SHOULD be distance or placement, correct? and 1 ball is dropped above the ground so I assume the answer is B since it has a line starting above the...
  40. Philethan

    A ball rolls without slipping in a cylindrical trough

    Homework Statement A solid sphere sphere (radius = R) rolls without slipping in a cylindrical trough (radius = 5R) as shown in the following figure. Show that, for small displacements from equilibrium perpendicular to the length of the trough, the sphere excuses simple harmonic motions with a...
  41. M

    What is the Velocity of the Ball Leaving a Racket Moving at 60 mph?

    Homework Statement A player swinging a tennis racket comprises a very heavy flat object (the racket-arm body combination) which makes a head-on collision with a very light object (the 2 ounce ball). The ball leaves the racket according to the formula: Vball = ε × Vracket The United States...
  42. N

    Rate of Change for Ball Thrown: How to Use the Formula f(b)-f(a)/b-a

    Homework Statement The Attempt at a Solution As far as I know those are correct. Could I have some assistance on how to solve for the rate of change? I know the formula is f(b)-f(a)/b-a but not sure how to go about it
  43. K

    Work and Energy of wrecking ball

    Homework Statement A wrecking ball swings at the end of a 10.0-m cable on a vertical circular arc. The crane operator manages to give the ball a speed of 6.00 m/s as the ball passes through the lowest point of its swing and then gives the ball no further assistance. Friction and air resistance...
  44. L

    What is faster the cannon ball or its shadow?

    I'm trying to finish my physics homework and one of the questions is somewhat philosophical. Problem: A cannon ball is shot at noon (12pm), what is faster? The cannon ball or its shadow? That's all the question is :p
  45. C

    A woman throws a ball at a vertical wall d = 5.0 m away.

    A woman throws a ball at a vertical wall d = 3.2 m away. The ball is h = 1.6 m above ground when it leaves the woman's hand with an initial velocity of 14 m/s at 45°. When the ball hits the wall, the horizontal component of its velocity is reversed; the vertical component remains unchanged...
  46. terryds

    Ball hitting an inclined plane

    Homework Statement http://www.sumoware.com/images/temp/xzafcttptkeoehmo.png An inclined plane is put on a smooth floor. The inclined plane is hit (collided) by an elastic ball moving horizontally before the collision. The ball bounce from the inclined plane and land again right at the point...
  47. terryds

    Ball sliding on 3d-inclined plane

    Homework Statement http://www.sumoware.com/images/temp/xzdmdjtlksnfhiqc.png A solid ball rolls perfectly with initial velocity v0 in horizontal axis ( y-axis ) on an inclined plane with elevation angle Θ as the picture above shown. This ball moves turning due to the gravitational acceleration...
  48. I

    Work done by Air resistance on ball?

    Homework Statement Hey! Problem: A ball falls 8,5 meters, and hits the ground with 11 m/s. The ball has a mass of 0,2 kilos. How much work was done by Air resistance on the ball? Homework Equations I guess mechanical energy eqution? The Attempt at a Solution answer should be -4,5 joule...
  49. Mewniew

    Solving for Initial Velocity of a Ball on a String | Physics

    Homework Statement (Im translating this from another language, so if it doesn't make any sense, please let me know and ill try to do a better job.) A metal ball (mass=120g) is hanging from a string (lenght=85cm). The ball is struck horizontally. When the angle of the swing reaches 125 degrees...
  50. T

    Find potential of a ball inside a grounded shell

    I have this question that initially a metal ball of radius r1 with potential v1, then surrounded by a conducting shell with radius r2. Find potential of ball if shell grounded. So v1 =kq/r1, then q=vr1/k, can I say directly that shell will have -q since it's induced by ball? Then v ball will be...
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