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. F

    Confused...calculating energy in a spring before launch of a ball

    Homework Statement So a little background before stating the problem: During a lecture a couple weeks prior to lab, the instructor did an example where we were told to find the max height of a ball launched upwards by compressing a spring. In order to calculate that, he showed that E1 is the...
  2. carb

    Ball equilibrium between 2 slopes

    Hello, Could somebody help me finding the relation between the horizontal force, the weight acting vertically, and the slopes Angle (same for both) that correspond to static equilibrium of the blue ball ? In a first step, I'd like to study this problem without considering friction at all. And...
  3. B

    Calculating Acceleration of a Ball Rolling Down a Slope

    Homework Statement A ball is placed at the top of an 8.5 meter slope, which is at an angle of 2.2 degrees. What is the ball's acceleration? θ of ramp=2.2 length of ramp=8.5 initial velocity (x and y)=0Homework Equations a = (v - v0)/t The Attempt at a Solution I tried for 45 minutes to solve...
  4. A

    What Is the Minimum Velocity Required for a Sphere to Overcome a Step?

    Homework Statement A uniform solid sphere of radius R rolls without slipping at velocity V on a level surface. It collides with a step of height h. Assume that after the collision, the sphere maintains contact with the step at point A with no slipping. Find the minimum value of V for the...
  5. K

    Gravitational force of a basketball to a golf ball

    Homework Statement Two basketballs, each of mass 0.58 kg and radius0.12 m, are placed on a floor so that they touch each other. Two golf balls, each of mass 0.045 kg and radius 22 mm, are placed on a table so that they touch each other. What is the ratio of the gravitational force exerted by...
  6. E

    How far does the ball go down the ramp

    Homework Statement A ball is shot out of a gun with an initial speed of 110 m/s. The acceleration of ball is -6 m/s^2 as it goes up an inclined plane of 1 m, which makes a 30 degree angle with the horizontal. Once the ball reaches the top of the inclined plane, it is launched off onto another...
  7. R

    Work done by a person lifting and then throwing a ball

    If I lift a ball of mass 5 kg from ground level to 1.5 meters above ground level and then throw it from this point up to a height of 10 meters, what is the work done by me on the ball? Is the following the correct way to solve this problem? Person only applies force to the ball for 1.5 meters...
  8. faiziqb12

    Calculating Force on a Ball at an Angle

    Homework Statement a mass of 100g strikes the wall with speed 5 m/s at an angle of 60 degrees to the wall and it rebounds with the same speed. if the contact time is 2 * 10^ -3 , what is the force applied by the wall and in what direction? The Attempt at a SolutionI tried solving the question...
  9. Emely

    A ball is thrown straight up from ground level

    A ball is thrown straight up from ground level. After a time 6.1 s, it passes a height of 136.1 m. What was its initial speed? The accelera- tion due to gravity is 9.8 m/s2 . Answer in units of m/s. Homework EquationsThe Attempt at a Solution
  10. E

    If I throw an iron ball at a magnet, the ball will bounce of

    Heat seems like the easy answer, but interparticle collisions should decrease as the ball slows.
  11. D

    Coulomb's Law: Calculating the Force between Two Charged Balls

    Homework Statement A small ball has been loaded so that its charge is -2.6 nC. Another similar ball has the charge +1.2 nC. The balls are located at the distance 2.5 cm from each other . With how much force do the balls attracts each other? Homework Equations F = k * (Q1 * Q2)/r2 The...
  12. M

    A rolling ball accelerating down an incline

    Homework Statement source:http://www.wired.com/2014/07/a-rolling-object-accelerating-down-an-incline/ For a ball rolling on an incline, I know how to calculate the acceleration. However, I am quite confused about a situation. What if static friction acting on the ball is equal to the...
  13. B

    A feather and a ball falling with air resistance

    Homework Statement Suppose you drop a feather and a steel ball of equal masses (0.014 kg) at the same time from a height of 2.2 m and you are told that the feather hits the floor 3.5 s after the steel ball. Estimate the value of the terminal velocity of the feather in air. Then, estimate the...
  14. toboldlygo

    "A woman throws a ball at a vertical wall...." Proj. Motion

    So, I've already answered parts (b) and (c), but I'm struggling with (d). Thanks in advance for any help! 1. Homework Statement "A woman throws a ball at a vertical wall d = 6.0 m away. The ball is h = 3 m above ground when it leaves the woman's hand with an initial velocity of 16 m/s at 45°...
  15. N

    If we neglect air resistance, then the range of a ball

    Homework Statement If we neglect air resistance, then the range of a ball (or any projectile) shot at an angle θ with respect to the x-axis and with an initial velocity v0, is given by R(θ)=v_0^2/g sin(2θ) for 0 ≤ θ ≤ π/2 where g is the acceleration due to gravity (9.8 meters per second per...
  16. NinjaChachi

    Magnitude of the average force exerted by ground on a ball.

    Homework Statement Just before hitting the ground, a partially inflated 0.625kg basketball has a speed of 3.30m/s. Then it loses half of its kinetic energy as it bounces. (A)What is the ball's speed immediately after it bounces?(B) If the ball is in contact with the ground for 9.25ms, what is...
  17. J

    What is the speed of the ball when it hits the ground?

    Homework Statement A ball is thrown from the edge of a 10.0 m high cliff with a speed of 20.0 m/s at an angle of 30 degrees below horizontal. What is the speed of the ball when its hits the ground below the cliff? Options : 1) 26.3 m/s 2) 28.1 m/s 3) 31.4 m/s 4) 24.4 m/s 5) 29.5 m/s I am new...
  18. Ryan_m_b

    Maximum height of ball with changing acceleration

    I put basic on this because my maths skills are exactly that and I suspect the answer to this question will be fairly maths heavy. I understand that the equation to calculate the maximum height of a projectile (ignoring wind resistance) is Hmax = (Vf2 - Vi2)/2a But this only works over small...
  19. Arlan

    Calculating Rebound Height for a Ball Colliding with Steel Plate

    Question: The coefficient of restitution for ball colliding with steel is 0.95. If ball is dropped from height h sub o above steel plate, to what height will the ball rebound? Please help me with this one, Is there a formula for this? all I know is e equals velocity of the first object...
  20. ProjectTruth

    How Much Does Each Golf Ball Cost in This Algebra Problem?

    << Mentor Note -- Thread moved from the technical math forums, so no HH Template is shown >> Hey guys, could use some insight here... So this is a basic story problem: "I paid $22.30 for 6 new golf balls and 10 used balls. If each new ball costs $.65 more than a used ball,how much did I pay...
  21. C

    What is the initial velocity of the ball just as it enters the screen?

    Homework Statement What is the initial velocity of the ball just as it enters the screen? The Job Using your understanding of projectile motion along with some background research on video analysis, devise a way to find the initial velocity of the tennis ball in the video just as it enters...
  22. C

    Ball Momentum After Paddle Collision

    I am currently trying to program a simple game in which a ball bounces of a paddle to hit blocks, and the game ends when all the blocks are broken. However, I know that when the paddle is moving in one direction, when the ball collides with the moving paddle, the ball should bounce of with a...
  23. F

    What is sign of y if ball is thrown up?

    This is a general question that i am confused about. If I throw a ball up, then is the distance that it reaches at the very top the y or y-initial? Also, is this y or y-initial positive or negative?
  24. R

    Center of mass of medicine ball

    Homework Statement 1.68 - ((51(0) + 109(1.5) + 66(3) + 13(0))/(51 + 66 + 109 + 13)) [/B] A person with mass m1 = 51 kg stands at the left end of a uniform beam with mass m2 = 109 kg and a length L = 3 m. Another person with mass m3 = 66 kg stands on the far right end of the beam and holds a...
  25. H

    Launching a ball with a flywheel design into a goal

    Hello all, My robotics club at school will be entering the VEX Nothing But Net competition. We are beginning to design the robot and it's launcher specifically. We want our flywheel design to be two wheels on each side, on a horizontal line like this. We would squeeze the balls between the...
  26. S

    Kinematics moving ball problem

    Homework Statement A ball moving westward at 36 m/s hits a wall and rebounds at 27 m/s, eastward. (a) What is the change Δv in the vector velocity? (This is effectively the velocity of the rebounding ball relative to an image of it passing through the wall unaffected. It’s not the same as the...
  27. B

    What is the smallest ball that can carry one esu?

    Suppose I want to collect 1 esu (2.081 billion charges) on a plate or on a ball, what is the smallest radius that will carry such a charge? From data I gathered around a ball of 1 mm of radius would be large enough, can you confirm that? What material is best, steel, silver or non-conductive...
  28. P

    Project: Ball Launcher - Calculate Torque and RPM

    Hi! I am making a physics project and I need to throw a ball to a target which is 5 meters ahead. I will use 2 counter rotating wheels to throw the ball but I have no idea what should motors torque or rpm should be. I tried to calculate it with determining the velocity first but the ball needs...
  29. A

    How can I calculate the cooling time for a ball of iron?

    Homework Statement A boll of iron with the volume ##V=\frac{4 \pi 0.01^3}{3}## heats up to 1073 K in a chamber with vacuum, how long will it take until the iron is at 1063 K? The given data is this: ##\rho_{iron} = 7870 kg/m^3## specific heat.. ##c_i = 0.5 \cdot 10^3 J/(kg \cdot K)##Homework...
  30. B

    Throwing a ball from a train at an angle

    Hi all, I've been trying to find an answer to this question for a while, (bear with me physics is not a strong point). I would like to know how one would go about calculating how fast you have to throw a ball out of a train to negate its forward momentum. My understanding is that if you throw...
  31. Z

    Ball fired from cannon homework

    Homework Statement A cannon, when aimed vertically, is observed to fire a ball to a maximum height of L. Another ball is then fired with the same speed, but with the cannon aimed up along an incline of length L, inclined at an angle θ. What should θ be so that the ball travels the largest...
  32. J

    Acceleration of a ball thrown vertically upwards

    Homework Statement I chose A because since the acceleration of the ball is positive vertically upwards, the acceleration downwards is negative, and at the turning point, acceleration is zero.. The correct answer is B. Why?
  33. X

    Calculating acceleration of ball rolling down ramp

    Homework Statement Hi, I know the acceleration of steel ball rolling down the inclined track is 5/7 * gsin(theta). But is it possible to find the acceleration of ball rolling on the inclined track just by using the distance traveled on the horizontal plane(attached to the Inclined track) and...
  34. E

    Speed of bowling ball involving speed of sound

    Homework Statement A bowling ball traveling with a constant speed hits the pins at the end of a bowling lane 16.5 m long. The bowler hears the sound of the ball hitting pins 2.5 s after ball is released from his hands. What is the speed of ball, assuming speed of sound is 340 m/s? Homework...
  35. L

    How Does a Cricket Bat Affect the Force on a Ball?

    Homework Statement This is a research problem, these are the figures I have at the moment I don't believe I need anything else to solve this problem (maybe the weight of the bat? it's stationary rather than swinging so I don't think it matters). A cricket ball weighing 0.159kg is bowled at...
  36. D

    Kinematics Tennis Ball Problem

    Homework Statement ) You are given the task of shooting a tennis ball from ground level through 2 hoops. The two hoops’ centers and the launch site are located in the same vertical plane, and the hoops are oriented perpendicular to the ball’s proposed trajectory and also in a vertical...
  37. E

    Force exerted on Earth by accelerating ball

    Homework Statement When a ball is bounced from the ground, the Earth exerts the force necessary to reverse its velocity. Is there a simultaneous force exerted on the earth? If there is one, why don't we perceive any acceleration of the earth? Homework Equations Newton's second law: net F=ma, F...
  38. A

    Ball Launcher Project for school (hit the target)

    << Mentor Note -- this thread is temporarily being allowed in the technical Engineering forums as long as the OP does the bulk of the work >> Here's the deal, I have to create a device that can launch ball, that bounces into a target that is 5 meters away. The targets are circular, one is 22"...
  39. I

    Physics behind inflatable ball collision

    Hello all, I've seen the videos many times before, where two people run at each other with giant inflatable balls and one of them will go flying while the other will hold their ground. I always wondered what is responsible for one person being propelled into the air while the other person feels...
  40. J

    Mechanics Question -- Ball bearing on top of an accelerating car

    Homework Statement A ball bearing rests on a ramp fixed to the top of a car which is accelerating horizontally. The position of the ball bearing relative to the ramp is used as a measure of the acceleration of the car. Show that if the acceleration is to be proportional to the horizontal...
  41. B

    Calculating Time for Ball to Reach Fence Plane

    Homework Statement Determine the time it takes for the ball tor each the plane of the fence. Answer in units of s. (VIEW IMAGE ATTACHED) Homework Equations Vf+vi+at d=vit+.5at^2 vf^2=vi^2+2ad The Attempt at a Solution [/B] I found Vix to be 11.59 using trig. I then used the second equation...
  42. B

    Projectile Motion: Calculating Speed of Ball Thrown from Third Floor Window

    << Thread moved to the HH forums from the technical physics forums, so no HH Templatge is shown >> So I have this question that says, "Someone at a third floor window (12 m above ground) hurls a ball downward at 45 degrees at a speed of 25.0 m/s. How fast will it be traveling when it strikes...
  43. D

    Acceleration of ball due to gravity

    Homework Statement So I know this is a super basic question, but my teacher and I have been going back and forth on this. If a ball is thrown up into the air, with no other forces acting on it, what is its acceleration? Isn't it - 9.8 m/s^2 because it is acting against the force of gravity and...
  44. Borek

    Melting Nickel Ball: Temperature & Radius Effects

    How far down can a nickel ball of radius r and temperature Tn melt into the ice block of temperature Ti? Watch the video and state your assumtpions...
  45. A

    Frictional Force on ball rolling down incline

    Hi everyone, For an experiment I wanted to investigate the forces acting on a ball when rolling down an incline. Basically I have a wooden incline with a photogate at the bottom to measure the velocity of the ball at the bottom of the ramp. At the top of ramp the sphere has potential energy...
  46. N

    Solving a Kinematics Problem: Throwing a Ball to Clear a Peaked Roof

    Homework Statement A peaked roof is symmetrical and subtends a right angle, as shown. Standing at a height of distance h below the peak, with what initial speed must a ball be thrown so that it just clears the peak and hits the other side of the roof at the same height? Diagram...
  47. W

    A ball is thrown up at 20 m/s at an agle of 15 degrees

    Homework Statement A ball is thrown upwards at 20 m/s at an angle of 15 degrees to ground. How long until the ball touches the ground? Givens for vertical: Acceleration = -9.8m/s2 v1= 5.2 m/s (20SIN15) v2=0 displacement=0 t=? Givens for horizontal Acceleration= 19.3 m/s (20COS15)...
  48. A

    Bounce Physics of Ball in Unity Game - Alex

    I am making a game where a ball rolls along the ground collecting coins. The ball is inside four walls. I want to know what the equation for the ball hitting the wall and coming back is. I want the speed and to find the angle aswell. The ball stays at a solid speed of 10 and has a mass of 1 kg...
  49. Priyadarshini

    A Ball Is Thrown Vertically Upwards, Find The Ratio of PE to KE

    Homework Statement A ball of mass 65 g is thrown vertically upwards from ground level with a speed of 16 m s–1. Air resistance is negligible. The ball takes time t to reach maximum height. For time t 2 after the ball has been thrown, calculate the ratio of the potential energy of ball to the...
  50. K

    Bullet stuck into a ball and rotates it

    Homework Statement A ball of mass M and radius R can rotate round an axis through it's center. a bullet of mass m travels with speed v, hits the ball near the surface and gets stuck in it. What's their angular velocity after the collision. Homework Equations Moment of inertia of a ball round...
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