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. K

    Power lines from an electrically charged ball

    Homework Statement A conductive ball of diameter 0.4 [m] is charged equally with a concentration of \sigma=8 [micro-coulon/m^2]. What's the total number of electric field power lines, N, that extrude from the ball Homework Equations The electric field near a conductor is like in a capacitor...
  2. B

    Calculating Tension when you swing a ball around a piece of string

    Homework Statement You swing a ball around a piece of string(vertically). M = 0.150kg r= 1.10m Calculate the Tention at the bottom of the arc assuming velocity is twice as fast. Homework Equations When I do the problem I'm not sure how to set up the NetForce = ma How do which force is...
  3. S

    Why Does an Accelerometer Show Zero During a Ball's Flight?

    I have a cricket ball and I place a dual axis accelerometer on it and throw is up in the air and catch it repeatedly. What would I expect its acceleration trace to look like. I am getting myself confused as I think there is an error in my trace.
  4. L

    Solving Rolling Bowling Ball Problem: Motion & Friction

    Hi everyone, this problem involves smooth rolling and translational motion: 1. Homework Statement A bowler throws a bowling ball of radius R= 11 cm along a lane. The ball slides on the lane with initial speed vcom = 8.5 m/s and initial angular speed w0 = 0. The coefficient of kinetic friction...
  5. G

    Find Forces on Hand and Arm Holding a Ball

    Homework Statement When an object is static (not moving), forces and moments must balance to zero. A moment here is defined as the force applied to an object multiplied by the distance from the point of rotation (torque). A simple way of thinking about moment balances is to consider a seesaw...
  6. P

    Small Ball Falling: Velocity, Acceleration & Height vs Time

    1.Small ball with mass m falls from hight h. Find how velocity, acceleration and height depend on time. Air resistance is linear and depends on velocity ##F = kv##. 2. Air resistance ##F=kv## where ##k## is constant. 3. I do not know where to go after ##ma = mg - kv ##.
  7. C

    Creating a Numerical Model for a falling Ball

    Homework Statement A ball was dropped through a known vertical distance with the time of drop also recorded. The aim of the task is to create a numerical model in excel in order to approximate the drag coefficient. Homework Equations This is my method. 1. FBD for the ball falling. (assume...
  8. L

    What are the Forces Behind the Color-Changing Switch Pitch Toy?

    Hello, I've come across this toy called a "Switch Pitch" designed by Chuck Hoberman. It's a ball that when tossed into the air (with some amount of rotation), inverts and changes colour. Made of plastic, it's connected with numerous sockets and plates. It's quite hard to describe with words...
  9. Y

    Build a Tennis Ball Launcher: Trebuchet vs Spring Cannon

    Hey all, I need to build a launcher that is capable of throwing a tennis ball over a 1 meter high wall and hit a target 2 meters away. I realize there are some threads already discussing this, but my question is more based on the type of launcher. Would a trebuchet or a spring powered cannon be...
  10. P

    Conceptual understanding of moment transfer for bouncing ball

    Hi, I am trying to wrap my head around what happens when a ball of mass m bounces against a hard floor. I assume a system that includes the ball and the floor (and eventually the entire planet) and an elastic collision. Before the ball hits the floor it has a momentum of mv. After the bounce...
  11. Satvik Pandey

    How Does Firing a Cannonball in Space Affect an Astronaut's Rotation?

    Homework Statement An astronaut in space weights 100 kg and is holding a cannon which can shoot a 10kg cannonball. The astronaut is moving at 10 m/s. The astronaut wishes to fire the cannonball such that he turns the maximum possible angle. Find this angle in degrees. Homework EquationsThe...
  12. B

    Why Don't Positive Charges from a Pith Ball Move to a Negatively Charged Rod?

    Hello guys, I'm curious in this phenomena: http://www.beaconlearningcenter.com/documents/492_01.pdf. In the second case, why don't the positive charges from pit ball move to the rod which is full of negative charges. If this happened, we would get a neutral rod and a negative pith ball... But...
  13. K

    Impulse and Coefficient of Restitution from Ball Drop

    A 1.2kg ball dropped from a height of 3m onto a steel plate rigidly attached to the ground bounces back up to a height of 2.5m.(a). What is the impulse delivered to the ball by the plate? (b). What is the coefficient of restitution of the collision?I know my instructor wants me to use something...
  14. N

    What Are the Electric Field and Potential in a Non-Conducting Hollow Sphere?

    Homework Statement https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-xaf1/v/t1.0-9/10155063_1485929725016579_7557468199677155885_n.jpg?oh=d575aa48176de7ecda27201b7ce35a5b&oe=54F7F368&__gda__=1425195231_44abd00cc231109df2fbe8d44cef9869 Homework Equations ∫E⋅da⋅n = 4πkQenc ΔV(voltage) = -∫Edr...
  15. P

    Question on a ball dropping( conservation of energy)

    Homework Statement A ball of mass 1 Kg is dropped from a height of 7m and rebounds to a height of 4.5m Calculate: its kinetic energy just before impact the initial rebound velocity of the ball and kinetic energy. Account for loss of kinetic energy on impact...
  16. K

    Ball caught by player, solve quadratic equation

    Homework Statement First part of the question (SOLVED) A football player kicks a football so that the angle of incidence is 50 DEG and the initial magnitude of velocity of the ball is 15 m/s. Find the: a) Balls maximum height = 6.7 m b) Time of flight = 2.3 s c) time when the ball reaches...
  17. T

    What is the velocity of the ball after H height? Considering wind resistance?

    I've been trying to figure out this problem for hours my whole group and most of the class is stumped. We understand that we need to relate the equations of F=ma, Fd = (Cd*p*v^2*A)/2, Fnet=Fd-Fg. No data is given. The answer is a V=____ equation. Even just an answer to #1 would be very helpful...
  18. HaLAA

    Calculating Impact Speed of a Ball Thrown Toward a Cliff

    Homework Statement A ball is thrown toward a cliff of height h with a speed of 28.0 m/s and an angle of 60.0° above horizontal. What is the ball's impact speed Homework Equations Vf=Vi-at Sf=Si+Vit-1/2gt^2 Vy=sintheta Vx=costheta The Attempt at a Solution first find the vertical velocity =...
  19. E

    Ball speed on a rolling surface?

    A couple friends and I were brainstorming an idea today and thought of a way to make a pump using the waves in the ocean for enrgy. So what it comes down to is say a 6cm i diameter steel ball in a tube, each side of the tube could have "pillows" that are part of a "membrane-pump". When the...
  20. powerof

    Solving for v_y max in a Spin-Friction Free Tennis Ball Model

    Homework Statement Title might be unclear since I had little space to explain. I'll state my problem from the beginning: I don't know how to determine one of the constants in formula for the velocity (the maximum velocity on the y-axis to be precise). I need that constant because I want to...
  21. C

    Projectile Motion ball is thrown upward

    Homework Statement A ball is thrown upward at an angle of 30° to the horizontal and lands on the top edge of a building that is 20 m away. The top edge is 5.0 m above the throwing point. How fast was the ball thrown? Homework Equations xcos30 ysin30 The Attempt at a Solution Im not sure what...
  22. J

    What is the best method for designing a trigger system for a ball launcher?

    Hi, I'm working on a project, the project is to create a ball launcher. the ball being a squash ball. 3 balls must be loaded once only but be able to be fired individually. the energy used to fire these balls is 3 1m long bungee chords. this cannot be changed. there are 3 main parts to it.1...
  23. K

    Path of a ball thrown radially from a satellite orbiting Earth

    Homework Statement A satellite has a circular orbit 500 km above earth. A ball is thrown directly downwards radially at 20 m/s. Find the path of the ball relative to the satellite. Homework Equations mv^2/r=GMm/r^2 The Attempt at a Solution From the height of the orbit you can easily solve...
  24. H

    How Fast Does a Ball Travel When Dropped from 5 Meters?

    Homework Statement A ball is dropped from a height of 5meters a) what is the velocity of the ball when it reaches the ground ? explain Homework Equations velocity = displacement /timeThe Attempt at a Solution the velocity is increasing due the gravitation of Earth (as 9.8m/s) the ball is at a...
  25. H

    Ball thrown upwards: Acceleration and Velocity

    Hello, all! I was searching online for help w/ my Physics homework and I stumbled upon this website. New member here (: 1. Homework Statement A baseball is thrown directly upwards. a. Is there a point on the trajectory where the ball has zero velocity? Explain. b. Is there a point on the...
  26. I

    Friction Force of a rubber ball

    Homework Statement If a 2.5 kg rubber ball is rolled across the dry concrete floor with an acceleration of 4.0 m/s^2[E]. Determine the friction force required to stop the ball. (Drawing a free body diagram will help illustrate this situation) Homework Equations Fk= µk(Fn) F=maThe Attempt at a...
  27. A

    What is the momentum transferred in a rubber ball collision?

    Homework Statement Homework Equations p=mv[/B]The Attempt at a Solution My thoughts- Answer is C as KE is not conserved since velocity of ball has decreased. Option A also seems correct.[/B]
  28. lovethepirk

    Golf Ball Backspin: Understanding Compression and Groove Effects

    Thanks in advance... I am trying to conceptually get my arms around backspin placed upon a golf ball when an angled(lofted) putter strikes a ball. -I'm assuming as you can see in the attachment that the two objects meet with the horizontal center of gravity at the same location so any twisting...
  29. B3NR4Y

    Bouncing Ball Dissipative Interaction

    Homework Statement A 0.62-kg basketball dropped on a hardwood floor rises back up to 64% of its original height. If the basketball is dropped from a height of 1.6m , how much energy is dissipated in the first bounce? How much energy is dissipated in the fourth bounce? Homework Equations U(x) =...
  30. H

    Range of Final Velocities in Collision of 10kg Ball and Sm. Mass Ball

    Homework Statement You have a 10kg ball that is going 10m/s. It is about to collide with a much less massive ball that is stationary. What is the range of final velocities of the small mass? All Collisions Are Elastic Given Case 1: The large mass stops after the collision. Given Case 2: The...
  31. A

    Two Balls Drop, what happens to the distance?

    Homework Statement Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. As time progresses, the distance between them A) increases. [<-- Correct Answer] B) remains constant. C) decreases. D) cannot be determined from the information given...
  32. Z

    Centripetal force of a ball swinging

    (Look at attached pic) The red ball is attached to a string which is being spun in a vertical circle. The downwards force is gravity and the other green one is the tension force. The blue is the sum of the green vectors. It is the centripetal force because it's the net force (and thus is equal...
  33. C

    A ball is thrown vertically upward.

    Homework Statement Describe what happens to its velocity as it moves up toward its peak. What is its velocity at its peak? Describe what happens to its velocity after it reaches its peak. Homework Equations The Attempt at a Solution No idea how to solve this.
  34. A

    Ball and Ramp: Solving for Time and Evaluating Position

    This is from a practice exam without an answer key. I tried the problem once before and am getting a different solution now. My method is solving for the time t when the x position is the width of ramp, and then evaluating y(t) to see if it is more or less than the height of the ramp. The...
  35. rakeru

    Rolling Ball and Proportionality Between Distance and Time

    Homework Statement A ball starts from rest and rolls down a hill with uniform acceleration, traveling 130m during the second 6.0s of its motion. How far did it roll during the first 6.0s of motion?Homework Equations I guess: v=v(0)+at v^2=v(0)^2+2ay x=x(0)+v(0)t+0.5at^2The Attempt at a...
  36. Bhupendra

    Solving for Equilibrium Forces on a 5kg Ball

    Homework Statement a spherical ball of mass = 5kg rests between two planes which make angles of 30 degrees and 45 degrees respectively with the horizontal . The system is in equilibrium . find the normal forces exerted on the ball by each of the planes . The planes are smooth . Homework...
  37. wonchristy

    Throwing a Ball on Mars: Exploring Height, Speed, and Time

    A ball is thrown with an initial speed of v0=39.2m/s vertically to Mars. Its initial height is h=15m from the surface of mars. the acceleration of gravity on Mars is g=3.7m/s^2 (1) what is the maximum height hmax of the ball (2) How long is the ball in the 'atmosphere' (3) What is the speed...
  38. AdoobII

    Projectile question -- ball rolling on a chair

    Homework Statement Hi all, in my grade 11 book there is a question, and the question is :- there is a ball rolling on a chair by a speed of 5.0 m/s on the X axis, the ball hit the ground on a distance of 0.25 m on the X axis, What is the Δy and what is the speed on Y axis ϑx (speed on X axis)...
  39. R

    Creating a Positive/Negative Magnetic Ball

    Is it possible to create a ball with a positive magnetic core and a negative exterior? And vice versa?
  40. P

    The Bouncing Ball Lab- Loss of Energy

    1. Okay. So, my lab is to bounce a ball at a given high while i calculate the time, mass, and different heights. Given these I find the PE, Velocity, and Difference in PE. I've gotten most of the lab complete but there is a final question that asks "If you wanted the golf ball to rebound to a...
  41. aditya ver.2.0

    Query regarding to the state of frame of reference for the ball

    If a metallic ball is place under a giant hollow top, and the top starts to rotate. Along with the top, the metallic ball will also start to rotate. Thus my question is the ball motion is under inertial frame of reference or non-inertial ?
  42. F

    What is the final velocity of the golf ball before it lands?

    A golfer hits a shot to a green that is elevated 3.00 m above the point where the ball is struck. The ball leaves the club at a speed of 17.1 m/s at an angle of 52.0˚ above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air resistance, find the speed of...
  43. A

    Find the force to stop a ball at a given speed

    Homework Statement Find the force to stop a 5kg ball at 20m/s instantly. Dont take in account resistance. Homework Equations kinetic energy = 0.5*mass*velocity^2 Energy = force * distance force = energy / distance The Attempt at a Solution 0.5 * 5kg * 20m/s^2 = 1000J 1000J / 0 =...
  44. PhysicsStudnt

    Ball dropped through a tunnel through the earth.

    Homework Statement A tunnel is drilled from the surface of the earth(mass assumed to be M and radius to be R) to its center . A body of mass m is dropped from the surface to the center through the tunnel. What will be the velocity with which the body of mass m will hit the tunnel...
  45. E

    Building machine to keep ball rotating

    I need a contraption that can keep a ball spinning, smoothly, at a slow speed. If it has a variable speed control, that would be better, but minimally it would need to spin a soccer ball and take around 30 seconds to make a full rotation. The look of the device doesn't matter, just that it...
  46. I

    A ball falls with no force acting on it

    If you are standing on the Earth and you drop a ball, the ball falls to the ground due to the force of gravity acting on it. Now imagine you are in an upward accelerating elevator in space. You let go of a ball that you are holding in your hand. The ball Is stationary in space, but the...
  47. D

    Collision of ball with a fixed inclined plane

    if a ball of mass m were to strike an fixed incined plane of 45degress with velocity of 3m/s, and was rebounded horizontally, what would be the velocity of the rebounded ball.(elastic collision). this the method i have tried. momentum of the system along the x-axis is conserved.therefore...
  48. M

    How Does Angular Momentum Affect a Ball Rolling Up an Incline?

    A hollow sphere with mass $$M$$ , radius $$R$$ , and moment of inertia $$I=2/3MR^2$$ about its center rolls without slipping with a initial center of mass speed $$v$$ towards a fixed ramp. It then rolls without slipping up the ramp. The ramp forms an angle $$\theta$$ with the horizontal...
  49. M

    Dropping a ball and calculating its speed.

    Homework Statement If a person drops a 20kg ball from a height of 50m. What is the speed of the ball before it hits the ground? Neglecting air resistance.The Attempt at a Solution I'm not sure if this is a trick question. The formula I would use to solve this is final velocity = initial...
  50. M

    Finding how long it will take the ball to reach 20m

    [b]1. The problem is the pitch was clocked at 160km/h and if a pitch were thrown horizontally with this velocity how far would the ball fall vertically by the time it reached home plate 20m away? [b]2. I used the average acceleration [b]3. t=d*average velocity t= 20m *...
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