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. I

    Snell's law problem about a hemispherical glass ball

    Homework Statement I have posted the snapshot of the problem. Homework Equations Snell's law equations The Attempt at a Solution Now the problem says that laser travels through air vertically upward to reach the outer surface of the glass half-cylinder. If that is the case, then from Snell's...
  2. ju456one

    Projectile Motion: Pitcher throwing a ball to a catcher

    Homework Statement determine the acute angle (in radians) of appropriate elevation in the throwing of a ball, if the initial velocity is 20 m / s, g=9.81 m/s^2 and the distance in x is 40m. The ball leaves the hand of the pitcher with an elevation equal to 1.8m and the catcher receives it at...
  3. S

    Exploring Conservation of Energy: Ball Dropped in Water

    My question: Consider an isolated system consisted of a ball, and a bucket of water. The ball is released from height, H above a bucket of water. The initial temperature of the water-bucket system and the ball are T1 and T2 respectively. What will be the final temperature of the water after the...
  4. B

    Angular and Linear Momentum Problem

    Homework Statement A system has a ball and a uniform rod. The rod is rotating about point X on a frictionless table until it strikes the ball. The rod stops and the ball moves away. Variables: Rod's mass: m1 Ball's mass: m2 Rod's original angular velocity: ω Ball's final velocity: v Rod's...
  5. C

    Hard Kinematics problem: Ball thrown into the air

    Homework Statement A person throws a ball up from a height of 1.5 meters, 3.23 seconds later, the ball hits the ground next to you. Find the maximum height the ball reaches. Homework Equations V=V(initial)+at The Attempt at a Solution This problem almost seems impossible without knowing what...
  6. S

    Swinging Ball at Top of Circle: Forces & Energies

    A 0.160 kg ball attached to a light cord is swung in a vertical circle of radius 70.0 cm. At the top of the swing, the speed of the ball is 3.26 m/s. The centre of the circle is 1.50 m above the floor. a. Draw a free-body diagram of the forces on the ball at the top of the swing. b. Calculate...
  7. Specter

    Velocity of the ball when it hits the ground, limits?

    Homework Statement [/B] The path of a baseball relative to the ground can be modeled by the function ##d(t)=−t^2+8t+1## , where d(t)represents the height of the ball in metres, and t represents time in seconds. What is the speed of the ball when it hits the ground? Homework EquationsThe...
  8. Justin71

    Torque Calculation for Screw Ball: TL Preload Nut

    Hi I don't understand what Fa mean ? This the weight or no ? And i don't understand too why in the torque TL, we have an additional part with the preload, the internal friction coeff of preload nut ... What is it ? Thanks.
  9. T

    A ball (sphere) rotating along a moving incline

    Homework Statement We have a ball of mass ##m##and radius ##r##. it is placed on an incline (We don't know the angle of the incline, nor we do whether the angle is constant along the incline - maybe it is a curved incline) and then released. The COM of ball is ##h## meters above the incline at...
  10. Tyrannosaurus_

    Problem solving: ball drops & ball shot up - they meet where?

    Homework Statement Ball 1 falls from rest from 67 m up. Directly 67 m below, ball 2 has 20 m/s [up]. No air. Where do they meet? Homework Equations non-uniform motion, so key kinematics equations. The Attempt at a Solution d1 + d2 = 67 m <--- is this okay to do? v1i *t + 1/2 a *t2 + V2i...
  11. Mmarzipan

    Collision with a ball spinning about its vertical axis

    Homework Statement A ball A is rotating on a table with an angular velocity ω about its vertical axis. An identical ball B collides with the ball A elastically. After collision the ball A starts sliding over the table. The coefficient of friction is µ. Find: 1) the angle α between the angular...
  12. O

    Impulse and Momentum: Ball and cart connected by a cord

    Homework Statement [/B] A 1kg cart, a 0.1kg ball, and an elastic cord connecting the ball and the cart, are placed in a weightless environment; see Figure. The cart has the shape of a symmetric trapezoid with its left and right edges at a 60-deg angle from the vertical. It is also attached with...
  13. P

    Finding the mass of a ball and a rod using torque

    Homework Statement There is a diagram of a rod with its center of mass labeled and a ball hanging down from it, attached by a string. Two torques are applied on either side. You are asked to find the mass of the ball and the mass of the rod. Homework Equations Torque = Force * Lever Arm *...
  14. P

    Kinetic Energy & Momentum of a Ball released from Spring

    Homework Statement "A spring with a spring constant "k" is compressed 10 cm from equilibrium. A ball of mass 100 g is at rest next to it. The spring then decompresses quickly back to its equilibrium position causing the ball to shoot forward. If the spring constant is 500 N/m, what is the...
  15. A

    Speed of ball vs Acceleration of the ball?

    Homework Statement Homework Equations v = s/t a = v/t The Attempt at a Solution My thinking was that through this small distance of air since velocity would increase due to the change in position changing at an increasing rate and thus since velocity is increasing then obviously...
  16. S

    Potential energy of ball thrown upwards

    Homework Statement A 1.00 kg ball is thrown directly upward with an initial speed of 16.0 m/s. A graph of the ball's gravitational potential energy vs. height, Ug(h), for an arbitrary initial velocity is given in Part A. The zero point of gravitational potential energy is located at the height...
  17. M

    How to calculate rebound speed of ball hitting a wall?

    Homework Statement A ball of mass 0.075 is traveling horizontally with a speed of 2.20 m/s. It strikes a vertical wall and rebounds horizontally. Due to the collision with the wall, 20% of the ball's initial kinetic energy is dissipated. Show that the ball rebounds from the wall with a speed of...
  18. J

    MHB What is the probability that the ball was labeled

    A tank contains 50 balls. 10 are frosted (F) and labeled (L), 23 are mild (M) and unlabeled, 7 are frosted and not labelled (N), 10 are mild and labeled. 1. A ball is randomly selected from the tank and it was frosted. What is the probability that the ball was labeled? 2. The 1st ball was...
  19. Alexanddros81

    A ball bounces off a brick wall, Find the average acceleration

    Homework Statement Serway Physics Section 2.4 Acceleration 14. A 50.0-g Super Ball traveling at 25.0 m/s bounces off a brick wall and rebounds at 22.0 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 3.50 ms, what is the magnitude of the average...
  20. A

    How high does the ball rise on the non-slip surface?

    Homework Statement A solid ball with radius of 9.7 cm is released from the height of hs=88.1 cm on a non-slip surface. After reaching its lowest point the ball begins to rise again, on a frictionless surface. How high does the ball rise on that side? Express your answer in cm. Homework...
  21. YMMMA

    Why the large ball falls farther than the smaller one?

    Homework Statement A large and a small ball, made of the same uniform density foam, are released at the same time from a point 100 meters above Earth. After 1 second the large ball is observed to have fallen farther than the small ball. Which of the following explains this observation? (A)...
  22. Krushnaraj Pandya

    Inelastic collision of ball and rod - rotation problem

    Homework Statement A uniform rod of mass M and length l is hinged at the center. a particle of mass m and speed u sticks after hitting the end of the rod. find the angular velocity of the rod just after collision Homework Equations Energy conservation-0.5mu^2=0.5(m+M)v^2 Angular momentum...
  23. I

    Solving a Disappearing Voltage Puzzle: The Ball Cyclotron Project

    Homework Statement I'm making a ball cyclotron (https://rimstar.org/science_electronics_projects/ball_cyclotron_electrostatic_accelerator.htm) for a school project. To generate enough voltage, I'm using a Van der Graaf-generator. The problem is that all the voltage, which I can measure...
  24. YMMMA

    How far will the girl run before catching the ball?

    Homework Statement Below Homework Equations Y=1/2 *gt^2 X=Vt Vf=Vi+gt The Attempt at a Solution The ball will have the same final velocity as Its initial. So, using the last equation 0=5+gt, where g is 10. Therefore, time to reach the maximum height is half seconds. To reach the same height it...
  25. X

    Free falling ball with and without air resistance

    Homework Statement A 2 kg ball (k factor of 0.02 m-1) is in free fall. The initial downward velocity of the ball is 12 m/s. Find the difference in displacement after 1s both with and without air resistance. Homework Equations vf = vi + at y = yi + 1/2(vi+vf)t y - yi = vit + (1/2)At2 - (1/3)Bt3...
  26. physicsstudent101

    How to find distance when a ball rolls slope with angle?

    Homework Statement A) For a steel ball rolling down a 35 degree slope from a height of .5 m above the table, how far will the ball travel in the x direction if it launches horizontally from the table which is 1m high For the same ball rolling down a 45 degree slope from one meter high, what...
  27. A

    Finding Charge & Tension of a Suspended Cork Ball

    Homework Statement A charged cork ball is suspended on a light string in the presence of a uniform electric field. E=(3×10^5 N/C)i+(5×10^5 N/C)j. The ball is in equilibrium in the field. Find the charge on the ball. The acceleration due to gravity is 9.8 m/s2 . The mass of the ball is 0.7g. The...
  28. YMMMA

    Physics: Projectile Motion - Maximizing Soccer Ball Distance/Hang-Time

    Homework Statement The question is in the pic. Homework EquationsThe Attempt at a Solution I answered it B. Still i am not quite sure whether it is B or E. I assumed some numbers, though.
  29. T

    Calculating the force required to move a golf ball up a ramp

    Homework Statement Hello and good day, I am currently working on a design project which involves creating a golf ball collecting machine. The current design method involves the golf ball being swept up a ramp by rotating sweeping arms. I am trying to calculate the force required to push the...
  30. R

    What is the height of a ball after being in the air for T/4 seconds?

    Homework Statement A child tosses a ball directly upward. Its total time in the air is T. Its maximum height is H. What is its height after it has been in the air a time T/4? Neglect air resistance. Homework Equations y=vot +0.5 at² The Attempt at a Solution It is 1/4 H but I don't get exact...
  31. P

    A ball is dropped from the top of a building....

    Homework Statement A ball is dropped from the top of a building and falls vertically downwards. Air resistance can be neglected. After falling a distance d, the speed of the ball is v. Determine the speed of the ball (in terms of v) when it has fallen a distance of 2d. Homework EquationsThe...
  32. DracoMalfoy

    Kinematics: Ball thrown off of a building

    Homework Statement A ball is thrown off of a building in the +x direction at 10m/s. If the ball takes 2s to land, how tall is the building? Homework Equations Vf=Vi(a)(t) Δd=Vi(t)+1/2(a)(t) Vf^2=Vi^2+2(a)(Δd) Δd=1/2(Vf-Vi)(t) The Attempt at a Solution Vf: 0m/s Vi: 10m/s a: -9.8m/s^2 t: 2s...
  33. Blocky970

    Acceleration of a shot put ball

    Homework Statement looking for the acceleration a person exerts on a shot put ball. total distance equals 23m. Thrown at an angle of 37 degrees and accelerating it at a distance of over two meters. Homework Equations I am working with a group of three other girls who are just as lost as i am...
  34. J

    Calculating the distance traveled by a ball

    Homework Statement The start velocity of the ball is 3m/s upward direction. Ball reaches its highest point after 1.2seconds No air or other friction like that i need to find how far the ball has traveled after 0.4 seconds, and after 2.4 secondsi can't get the right answers, says its supposed to...
  35. A

    Projectile motion of a cannon ball versus time

    Homework Statement A cannon is inclined about the horizontal by an angle of 45° and it launches projectiles with initial velocity of ##v_p=300m/s##. A small airplane moves horizontally with a constant velocity of ##-100m/s##(so it is directed to the cannon) at high of ##500m##. If at ##t=0s##...
  36. O

    Please help prove this fact about a ball falling....

    Why is the time it takes for a vertically thrown ball to reach max height the same as the time it takes for the same ball to fall from max height to ground level? I agree with this logically but I can’t prove it mathematically... Can you please show me the mathematical proof for this fact...
  37. L

    Seperation between two charged ball

    Homework Statement Two identical insulating balls of mass m hang from massless strings of length l and carry identical electric charges, q. you may assume that the angle of separation θ is so small that tanθ ≅sinθ≅θ. What is the separation distance between the two masses x? The Attempt at a...
  38. R

    What causes a spinning ball to bounce forward?

    The ball is given no initial horizontal velocity. It is however given an initial angular velocity of 76 rad/s and allowed to drop vertically from a height of 0.835m. Right after the ball bounces its vertical velocity is 3.1m/s upwards and its forward horizontal velocity is 1.838m/s and the ball...
  39. opus

    B Parametric Equations- Ball travel

    Suppose a baseball is hit 3 feet above the ground, and that it leaves the bat at a speed of 100 miles an hour at an angle of 20° from the horizontal. I've got the parametric equations in terms of x and in terms of y, and I have values plotted and a graph sketched. My question is in regards to...
  40. Krushnaraj Pandya

    How is net torque zero about hinge of rod in ball rod system

    Homework Statement There are 2 situations- 1)a rod of length L is lying on a smooth horizontal surface with its one end hinged to the ground, a ball traveling with a velocity v hits its other end and comes to rest, How is the net external torque about hinge point O zero? 2) in the second case...
  41. M

    What's the speed of the ball 1 second after it was kicked?

    Homework Statement A soccer ball is kicked with an initial horizontal velocity of 15m/s and an initial velocity of 16m/s. What's the speed of the ball 1 second after it was kicked? Homework Equations Initial velocity = sqrt([horiz. Velocity]^2 + [vertical Velocity]^2) Final velocity = initial...
  42. Krushnaraj Pandya

    Height to which rolling ball rises on a surface

    1. The problem A ball moves without sliding on a horizontal surface. It ascends a curved track upto height h and returns. Value of h is h1 for sufficient rough curved track to avoid sliding and is h2 for smooth curved track, then how are h1 and h2 related (greater, lesser, equal or multiplied by...
  43. berkeman

    Soccer Ettiquette Question: Giving the ball back to the opposition

    I've seen this in local elite team play, and have seen it at least twice in the World Cup matches going on now (amazing come-back win by Germany yesterday, BTW). There seem to be some circumstances where a team will elect to give the ball back to the opposition, based on something that happened...
  44. I

    Find the launch speed of a ball in a spring mechanism

    Homework Statement I have a question asking me to find the launch speed of a ball (mass 0.39kg) when released by a spring mechanism made of 2 springs each with force constant 25Nm^-2. they are pulled back 12 cm. the ball is initially at rest.Homework Equations [/B] v^2=u^2+2as f=ma f=kx...
  45. Richie Smash

    How does ball A come to rest and Ball B remain stationary?

    Homework Statement In a collision between three identical steel balls A B C A comes to rest and B remains stationary, while C rolls off. In terms of the Forces acting, explain how Ball A came to rest and why Ball B remained stationary. Homework EquationsThe Attempt at a Solution Well what I...
  46. Gabriele99

    How long will the ball and the spring be in contact?

    https://physics.stackexchange.com/questions/407908/if-i-push-a-ball-on-a-string-till-this-is-completely-compressed-how-long-will-t. This is my complete question. I've been wondering on this topic for quite a while. I really can't visualize what happens at the border between the spring and the...
  47. A

    Kinetic energy of a bouncing ball

    Homework Statement I'm trying to find the coefficient of restitution (COR) and energy loss upon impact of a bouncing ball, and I'm trying to understand how these relate to each other. Homework Equations COR=sqrt(2gh/2gH) suvat equations (possibly) 1/2mv^2=mgH (using m=0.0585kg, g=9.8) energy...
  48. Zubair Ahmad

    Momentum Conservation: Ball Hitting Pivoted Rod

    If a ball hits a rod at the top which is pivoted at bottom end then is linear momentum conserved?
  49. S

    Sanity check on falling steel ball in water

    Homework Statement What is the speed of a 5 mm steel ball falling through water at 10 C[/B] Viscosity of water: 1.3059 * 10-3 Pa*s (Various online sources) Homework Equations Laminar flow: Vt = gd2 (ρp - ρm)/18μ Vt = terminal velocity g = gravity (10m/s2) d = diameter of ball ρp =...
  50. J

    Calculating Image Distance Using a Christmas Tree Ball

    Homework Statement You look at yourself in a shiny Christmas tree ball, which has a diameter of 9.63 cm. If your face is 7.81 cm away from the shiny ball, calculate the image distance. Homework Equations ? Thinking I would use magnification = di/d0 di = 0.0781m d0 = 0.0963m The Attempt at a...
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