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. S

    Which ball exerts a larger impulse on the wall?

    A 10 gram rubber ball and a 10 gram iron ball are thrown at a wall with equal speeds. The rubber ball bounces back at almost the same speed with which it was thrown at the wall, while the iron ball bounces back at half the speed with which it was thrown at the wall. Which ball exerts a larger...
  2. L

    Ball trajectory velocity and displacement vectors

    Homework Statement ball is thrown at slighta angle upwards and to the right. Angle between horizontal and the launch velocity vector is 35deg upwards. Launch velocity vector (v_0) has magnitude of 12m/s Only gravity affects the ball as a force. (no air resistance) t_0 = 0 secs t_1 = 0.2 secs...
  3. K

    MHB Extreme points of L^p[0,1] on unit closed ball

    I would like to prove that if $\|f\|_p = 1$ then $f$ is extreme point of unit closed ball in $L^p[0,1]$. [here $1<p<\infty$] I suppose we should try to prove it by contradiction. That is, if $f \in L^p$, with $\|f\|_p=1$, is not extreme, then exists $g,h \in L^p$ with $\|g\|_p,\|h\|_p \leq 1$...
  4. K

    A ball is shot from the ground into the air

    Homework Statement A ball is shot from the ground into the air. At a height of 8.8 m, the velocity is observed to be v = (7.4)i + (5.7)j in meters per second (i horizontal, j upward). To what maximum height will the ball rise? Homework Equations V^2 = Vi^2 + 2a(Δy) The Attempt at a Solution...
  5. moenste

    Ball speed at the top of the loop

    Homework Statement A compressed spring is used to propel a ball-bearing along a track which contains a circular loop of radius 0.10 m in a vertical plane. The spring obeys Hooke's law and requires a force of 0.20 N to compress it to 1.00 mm. (a) The spring is compressed by 30 mm. Calculate...
  6. moenste

    Reaction between a track and a ball at a point

    Homework Statement The diagram shows a section of a curtain track in a vertical plane. The curved section, CDE, forms a circular arc of radius of curvature 0.75 m and the point D is 0.25 m higher than B. A ball-bearing of mass 0.060 kg is released from A, which is 0.50 m higher than B. Assume...
  7. Austin Chang

    Projectile Motion of thrown ball

    Homework Statement A person throws a ball at a 45 degree angle and hits a given target. How much quicker does the ball get to the target if the person instead throws the ball with the same speed v0 but at the angle that makes the trajectory consist of two identical bumps, as shown (Assume...
  8. V

    How Do You Calculate Initial Velocity and Maximum Height in Projectile Motion?

    Homework Statement A baseball player throws a ball straight up and then catches ot 2.4 s later at the same heiggt from which he threw it. Determine the initial velocity and maximum height of ball? Homework EquationsThe Attempt at a Solution Im confused about how to find inital velocity. I know...
  9. F

    Ball hitting a wall with relativistic effects

    Homework Statement I have encountered a problem in Sean Carroll's GR book, exercise 1.1 Consider an inertial frame S with coordinates ##~x^μ = (t, x, y ,z)~##, and a frame S' with coordinates ##x^{μ'}## related to S by a boost with velocity parameter ##v## along the y-axis. Imagine we have a...
  10. E

    B Drop Ball Moving: Initial Velocity 0m/s?

    Hi I'm trying to solve a problem but I'm a bit confused about this part: Suppose you are walking at a speed of 2 m/s when you drop the ball that you were holding in your hands. Is the initial velocity 0 m/s? In the textbook it says that initial velocity for dropped objects is 0 m/s but that...
  11. X

    How Far Did the Ball Roll in the First 5 Seconds?

    Homework Statement A ball starts from rest and rolls down a hill with uniform acceleration, traveling 150 m during the second 5.0 s of its motion. How far did it roll during the first 5.0 s of motion? Vi= 0 at time t=5s -> d= 150 m Homework Equations d=vf+vi/2 * t The Attempt at a...
  12. P

    What Happens When You Bombard a Rubber Ball with Electrons?

    A friend of mine posed a question; if you take a rubber ball and bombard it with electrons, what would happen? I posited that some of the electrons would likely stay on the surface of the ball, giving it a negative charge. I then suggested that if under the "right" conditions you may be able...
  13. B

    Exploring the Complexities of Ball Movement on a Sloped Grass Surface

    Hello, I play bowls on outdoor grass greens. I studied physics in school, and I've been wondering how physics works on the bowls in different areas of the green. So for those who aren't familiar, you have a jack and a bowls. Jack is smaller and lighter, bowls larger and heavier. The bowling...
  14. C

    Quick throwing and dropping ball Question

    I am relatively new in understanding physics. I have a quick question that I think a lot of you will find easy to explain. Why is it that when a ball is dropped initial velocity is 0 but when it is thrown the initial velocity is not 0? Do they not both start at rest?
  15. Thejas15101998

    Wavelength of a Tennis Ball at 0 Velocity

    In the De Broglie equation : λ = h / (m v) what happens when the velocity of an object is zero? I see that we get ∞ wavelength . It is not making any sense to me. Could anyone please help me. Let's take the object to be a tennis ball say.
  16. Biscuit

    How many times will a ball bounce before coming to a rest

    I always enjoy physics questions that aren't super complicated and give me something to think about for a day or two. One that has recently come to my head is how many times will a ball bounce before coming to a rest. what formulas should I use to find this out.
  17. K

    Minimizing Friction for a Ball in a Rough Bowl: Accelerations and Velocity

    Homework Statement [/B] The ball of mass m and radius r is released from horizontal position, the edge of the bowl. What are the tangential and radial accelerations at angle θ and what is the velocity. What should be the minimal friction coefficient at angle θ so that the ball won't slip...
  18. Romain Astie

    Throwing a ball sideways vs. dropping it

    So here's my physics conundrum: I am on a ROUND Earth, in a vacuum. If I throw a ball really fast (say 99.9% of the orbital velocity for the ball's altitude), and drop another ball straight down, which takes longer to hit the ground? My basic physics reasoning would say that it takes the same...
  19. J

    A ball rolls on a horizontal table and drops. it hits the 0.

    Homework Statement it hits the ground 0.5s after dropping and at a 40cm distance from the table. what is the table height? what is the ball initial speed? in what speed (with direction) did it hit the ground Homework EquationsThe Attempt at a Solution solved thee first question stuck on the...
  20. UMath1

    Why is friction minimal in a non-ideal ball bounce situation?

    When a ball is bounced against a wall at an angle why is that the wall only applies a normal force perpendicular to the collision location? Shouldn't the force applied by the ball against the wall be along the line at which it travels, at an angle? Then by that logic, by Newton's 3rd Law...
  21. sunney

    B What Happens When a Ball Is Thrown in a Moving Car?

    acoording to theory of relativity, if a car is moving at a uniform speed then any object inside that car behave like its in rest. so what happens if a man throws a ball in an open roof car which is at uniform speed, where that ball is likely to land , assuming no other external force is...
  22. K

    Ball being hit starts to slide and roll

    Homework Statement [/B] A billiard ball of mass m and radius r is being hit and starts to slide on a surface with equivalent of friction μ. What is the friction force The distance to rolling only What is the energy loss in the sliding phase Homework Equations Kinetic energy of a solid body...
  23. MickeyBlue

    Relative velocity of a ball on a train

    Homework Statement A train is traveling east along a straight run of track at 72.0 km/hr. Inside, two siblings 1.9 m apart are playing catch directly across the aisle. The kid wearing a P.J.Harvey T-shirt throws the ball horizontally north. The ball crosses the train and is caught 0.75 s later...
  24. berkeman

    Exercise ball "chair" for work desk....

    Have there been any studies looking at the ergonomics of using an exercise ball as your work desk chair? I have a close friend with lower back and leg pain who is looking for ergonomics options. There are lots of studies about keyboard positions, etc. EDIT -- She is also talking to her doctor...
  25. Erenjaeger

    How Do You Calculate Initial Velocity in a Vertical Ball Throw?

    Homework Statement Concept Simulation 2.3 provides some background for this problem. A ball is thrown vertically upward, which is the positive direction. A little later it returns to its point of release. The ball is in the air for a total time of 8.21 s. What is its initial velocity? Neglect...
  26. The Bill

    I Radius of the largest ball inside a complex set.

    I've been thinking about notions like the following: "How far can one be from the nearest road while in a particular country." "What's the 'maximum thickness' of a subset of \mathbb{R}^n?" "What mountain range has the biggest circular region entirely within it?" These sorts of questions lead...
  27. K

    Ball Lightning: Uncovering the Mystery of N_7^{14}, H_1^1, & O_8^{16}

    Homework Statement Ball lightning is a sphere shaped lightning that stays long before it explodes. they are sometimes created in a lightning storm. The theory says they are made of nitrogen ions surrounded by water molecules. the temp' inside is 6000C and outside 200C. Nitrogen: ##N_7^{14}##...
  28. Zack K

    Applied force of a ball on a glove

    Homework Statement A 0.145 kg baseball traveling at 35.0 m/s strikes a catcher's mitt which, in bringing the ball to rest, recoils backwards 0.11 m. What was the average force applied by the ball on the glove Homework Equations Fnet=ma or F=ma The Attempt at a Solution I am honestly so lost...
  29. V

    Ball colliding with rod elastically

    Homework Statement Ans D) Homework EquationsThe Attempt at a Solution The problem I am having in this question is that mass and speed of ball is not given . I think it is not possible to solve this question without this data . Am I correct or is data sufficient in this problem ? Thanks
  30. A

    HW questions about Forces with ball examples

    Hey all, I'm don't have the firmest grasp on physics and a little help would be much appreciated! So two questions: 1)a physics student watching a tennis match states, "while the ball is in contact with the racquet, the racquet exerts a larger force on the ball than the ball does on the...
  31. Lechiam

    Sign of Acceleration of dropped tennis ball at the floor

    Homework Statement You drop a tennis ball on a hard floor, and it bounces upward. If the x-axis is directed upward, what is the sign of the acceleration while the ball is in contact with the floor? Homework Equations a=v/t The Attempt at a Solution I thought that the acceleration when the...
  32. N

    Electric field at the centre of a ball

    Question : Find the electric field at the centre of a ball of radius R with volume charge density rho = a.r, where a is a constant vector and r is a radius vector drawn from ball's centre. Relevant Equations and attempt at solution : I used the basic formula for electric field due to...
  33. S

    Thermal Radiation of a steel ball

    Why does a steel ball appear hotter than a charcoal piece at the same temperature when picked up by bare hands?
  34. J

    B Observer Sees When I Throw Ball at Speed of Light

    If I were of speed 299 792 457 m/s relative to an observer and throw a ball, what would the observer see?
  35. P

    MHB Which Person (if any) has a greater chance of picking out the Red ball?

    A) There are 5 balls inside bag A. They're all a different color (Red, Blue, Green, Orange, Purple). Person A has two attempts to pick a Red ball from inside bag A: 1st Attempt: 1/5 chance = 20% = Let's say Person A picked out a blue ball. 2nd Attempt: 1/4 chance = 25%. B) There are 4...
  36. BlueQuark

    Tension of wire attached to 45-kg ball.

    Homework Statement "A solid uniform 45-kg ball of diameter 32cm is supported against a verticle frictionless wall using a thin 30cm wire of negligible mass. A)Make a free body diagram for the ball and use it to find the tension in the wire. B)How hard does the ball push against the...
  37. S

    Bouncing ball and Doppler effect

    Homework Statement Consider two parallel walls perfectly reflective placed at the distance ##d = 0.8 m ##. A ball, provided with a device through which are emitted continuously frequency sound waves equal to ##f_0=430 Hz##, is launched from one wall to another. It moves with constant velocity...
  38. J

    Exploring Buoyancy: How Ball Moves in Water, Oil and Moon Gravity

    Homework Statement 1a)How does a ball floating 50% in water move when a LARGE amount of oil is added? 1b) if something denser than water were added, how would the ball move? 1c) if the exp. was done on the moon with different gravity and no atmosphere, how would the ball move?Homework...
  39. C

    A ball being hit, find the energies and maximum height

    Homework Statement The longest homerun hit by Miguel Cabrera in the 2012 season occurred at Comerica Park and had an initial y-component of velocity of 19.8 m/s and an initial x-component of velocity given as m/s, where is some value left undetermined. Assume the ball left the bat 1.22 m off...
  40. D

    Does the Soccer Ball Move If I Kick It with Equal Force?

    If i kick a soccer ball, the soccer ball exerts the same force on my foot as i exert of the ball. In that case, why does the soccer ball move at all. If the forces are equal should there be motion. I know it a dumb question but i need some deep explanation. Also can I exert force on something...
  41. M

    Fluid dymanics basics ball valve full open vs. half open

    is there any difference and why ? I have a ball valve with 100 psi jet fuel on one side and atmosphere on the other end ? Is there any difference if o have 100 psi and the valve all the way open vs. say 200 psi and only half way open . Please explain ?
  42. J

    Coefficient of restitution of a ball question

    Why is the coefficient of restitution of a ball independent of the height it is dropped from? A mathematical explanation would be best. Thank you.
  43. P

    Ball of gas experiences rapid increase in pressure....

    Homework Statement A self-gravitating ball of gas suddenly experiences a rapid increase in its pressure to a new value P'. Taking average density of the star to be ρ and radius R, and ignoring gravity altogether, estimate the time scale of expansion of the star. Homework Equations Force=...
  44. A

    Ball rotated on a string vector diagram

    Homework Statement is 1222.5i 1 20.2j2 m/s . For that instant, (a) sketch a vector diagram showing the components of its acceler- ation, (b) determine the magnitude of its radial accel- eration, and (c) determine the speed and velocity of the ball. 42. A ball swings counterclockwise in a...
  45. B

    High Pressure Sodium and Metal Halide lamps near plasma ball

    I bought one of these plasma globes, decided to do some experiments with it. Since a fluorescent bulb will light up if It's put near the plasma ball, i tried the same with two HID lamps. The Metal Halide shows a very pale white arc, which disappears as soon as the plasma ball is turned off...
  46. P

    Ball rolling down an incline gaining mass

    Homework Statement A snowball, initially of mass m, slides down a slope inclined at an angle φ with respect to the horizontal. As it moves, the mass of additional snow Δm = αx that it accumulates is proportional to the distance traveled x. Write the differential equation of translational motion...
  47. J

    Function for the velocity of a bouncing ball

    I graphed different heights from which I had dropped a bouncing rubber ball on the y-axis and the time taken for it to bounce on the x-axis. The function came out to be quadratic, but I do not know why. If someone can show mathematically why this is, that'd be splendid. Thank you.
  48. J

    What is the tension supporting one ball?

    Homework Statement Two identical conducting balls, b1 and b2, each with a mass of 25.0g both are hanging at 50.0cm at an angle of 45Degrees from the vertical each. Homework Equations Fg = mg Fe = kq/r^2 Ft = ? The Attempt at a Solution I made a free body diagram and am confused on what to do...
  49. S

    Ball on String, Calc V with mass, answer by "accident?"

    Hi all, concerned Dad here - looking for a validating opinion on the following and would be eternally grateful with some guidance/help. The attachment, Unit4ExamAQ7c is from one of my son's honor's exams. He gets #7c CORRECT with the answer v=2.29 m/s. However, the teacher grades him WRONG...
  50. U

    Ratio for the dimples in a golf ball

    I'm conducting an experiment in order to find the effectiveness of dimples in a golf ball when flying through the air. As part of the experiment, I'm planning on testing the different dimple patterns of various golf balls. However, I'm having trouble coming up with a numerical ratio that can...
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