Balls Definition and 541 Threads

  1. K

    Reliable Method for Launching Ping Pong Balls at Varying Speeds?

    Hello, I'm an electrical engineering student at Washington State University, and I am attempting to design a beer pong (more properly known as beirut) playing robot. It won't be completely autonomous, as you will still have to tell it when to shoot, and load the balls, etc. Anyway, all of the...
  2. M

    How Fast is a Golf Ball Traveling 10m After Being Dropped from a Cliff?

    Golf balls and cliffs! Hi I'm new to this forum and a novice in physics could anyone please help me with this question? A golf ball is droped from the top of a sheer cliff 78m high. If gravity is 9.8ms^-2 and there is no air resistance, what speed is it traveling at 10m from its initial...
  3. Ivan Seeking

    How to hallucinate with ping-pong balls and a radio

    http://www.boston.com/bostonglobe/ideas/graphics/011109_hacking_your_brain/
  4. B

    What Is the Charge on Each Pith Ball?

    Homework Statement Please check if i did this problem right.. two charged pith balls are suspended on very light 12. cm strings. Each has a mass of 10. . In equilibrium the total angle between the string is 50 degrees, Assuming that the pith balls are equally charged, what is the...
  5. N

    Balls and clay blob - Collision problems

    Homework Statement A ball of mass 9m is dropped from rest from a height H =5 meter above the ground. It undergoes a perfectly elastic collision with the ground and rebounds. At the instant that the ball rebounds, a small blob of clay of mass m is released from rest from the original height...
  6. K

    Electric field between two separated metallic balls.

    What is the electric field between two isolated metallic balls separated by a distance L, one having charge +Q and one having charge -Q? (Ball one and ball two have a surface charge 'sigma 1' and 'sigma 2' respectively). The +Q ball has a larger radius than the -Q ball.
  7. D

    Colliding balls with different masses

    2 balls, with masses of M1, M2, are involved in a plastic collision, one dimentional.. the kinetic energy of the ball m1 is 20 times that of m2. at what ratio between the masses will the new mass(m1+m2) move in the direction the lesser energy mass mas moving. from Ek1=20Ek2...
  8. A

    Balls exerting gravitational force on eachother

    Homework Statement Two balls, each with a mass of 0.790 kg, exert a gravitational force of 8.39 x 10^-11 N on each other. How far apart are the balls? The value of the universal gravitational constant is 6.673 x 10^-11 N m^2/kg^2. Answer in units of m.Homework Equations F = (G * m1 * m2) /...
  9. W

    Prove two metric spaces have the same open balls

    Homework Statement Let X be a metric space with metric d, and let d_{1} be the metric defined by d_{1}(x,y) = \frac{d(x,y)}{1+d(x,y)} . Show that the two metric spaces (X,d) and (X,d_{1}) have precisely the same open sets. Hint: show that they have the same open balls with one...
  10. T

    How can the dynamics of falling balls be analyzed using equations of motion?

    Homework Statement http://members.shaw.ca/code/balls.JPG" Homework Equations I'm not sure what equations to use here, or even wether or not I need to use calc. Unfortunately we just started dynamics and most students don't know how to integrate yet (including me) v = dx/dt a =...
  11. G

    How Many Ways to Partition N Balls into Subgroups with a Maximum of k Balls?

    Hello. I am trying to find out the number of options to divide N balls to subgroups in a way that each subgroup does not contain more than k balls. Any idea? Thanks!
  12. P

    Collision of Balls - Coefficient of Restitution

    Homework Statement Two equal balls are in contact on a table and are in equillibrium. A third ball collides with them simultaneously, symetrically and remains at rest after the impact. The coefficient of restitution is : A)2/3 B)3/2 C)1/3 D)1/2 Homework Equations The...
  13. F

    What is the peak force between two pool balls in a pool shot?

    Homework Statement What is the peak force between two pool balls in a pool shot? Estimate the momentum transferred to the object ball in a hard pool shot. Estimate (or look up) masses and velocities. For how long are two pool balls in contact? The time can be approximated by the length of...
  14. S

    Momentum Change and Impulse in Colliding Balls

    Homework Statement There are two balls traveling and they collide. How do there momentum change. What is the impulse done to ball B by ball A. Homework Equations delta momentum = 0 impulse = ? The Attempt at a Solution the first part i think its C becuz A is moving up and...
  15. N

    [Collision with 2 Clay Balls] [Inelastic Collisions] [Help Finding Theta]

    Here's my problem guys, I've been trying to puzzle this out for a while. Would really appreciate any help at all, thanks! Homework Statement A 50.0 g ball of clay traveling east at 5.50 m/s collides and sticks together with a 40.0 g ball of clay traveling north at 6.00 m/s. What is the...
  16. N

    Two Balls Thrown from Cliff: Speed of Impact

    two balls are thrown with equal speeds from the top of a cliff of height H. one ball is thrown upward at an angle @ above the horizontal. the other ball is thrown downward at an angle # below the horizontal. show that each ball strikes the ground with same speed and find that speed in terms of H...
  17. K

    Comparing Impulse in Collisions: Which Ball Experiences a Greater Magnitude?

    Homework Statement 2 equal mass balls (one red one blue) are dropped from the same height and rebound off the floor. the red ball rebounds to a higher position. which ball is subjected to the greater magnitude of impulse during its collision with the floor? a. it's impossible to tell...
  18. Z

    How many balls can this juggler juggle?

    A juggler has a set of balls that she can toss into the air. If it takes her 0.2 s to transfer a ball from the receiving hand to the launch hand and she is able to throw a given ball up with a maximum speed of 10 m/s how many balls can she successfully juggle at any time? Assume that the balls...
  19. M

    Kinematics equations with collision fo 2 balls

    Homework Statement a ball is shot straight up from the ground with speed Vo. simultaneously, a second rubber ball at height h directly above the first ball is dropped from rest at what height above the ground do the balls collide?asnwer should be a symbolic expression in terms of Vo and g...
  20. R

    Solving the Billiard Balls Problem: Collision Time and Angle Calculation

    Two billiard balls are moving on a (coordinatized) pool table according to the respective paths x(t)=(t2-2, \frac{t^2}{2}-1) and y(t)=(t, 5-t2) where t is time in seconds. a) When and where do the balls collide? I found where the 2 graphs intersect to be (2,1) so does that mean at 2 seconds...
  21. D

    When will both of the balls be at the same height?

    Homework Statement http://img228.imageshack.us/img228/7232/physicsku0.jpg http://g.imageshack.us/img228/physicsku0.jpg/1/ Homework Equations The Attempt at a Solution I'm extremely lost..
  22. D

    Identify Lighter Balls Weighing on Christmas Tree

    Weighing... On a Christmas tree there were two blue, two red and two white balls. All seemed the same, however in each colour pair one ball was heavier. All three lighter balls were the same weight, just like all three heavier balls. Using a pair of scales twice, identify the lighter balls.
  23. D

    Contraction of spring colliding with balls

    on a vertical spring (k=100n/m) there is a box with a mass of 5kg, a ball of 1kg is dropped into it from a height of 1m what is the maximum contraction of the spring if the collosion is plastic. i hope that my terminology is correct as i am not studying this in english and am translating...
  24. L

    Can Ping-Pong Balls Revolutionize Particle Acceleration?

    27 km ping-pong ball accelerator. http://www.sciam.com/article.cfm?id=large-hadron-collider-first-beam&sc=rss Well at least that works.
  25. S

    Identifying the Gold & Titanium Balls

    You have 2 balls. Both are identical in size and mass, but one is made of gold and is hollow,the other is not hollow and made from titanium. Find out which is which ball, and let's say both are covered with a black paint that is anti reflective, heat/electricity insulator. You can't use any...
  26. M

    Balls and bins problem from 'introduction to algorithms' textbook

    Hi Everyone, I've been trying to do the following problem, which is exercise 5.4-2 in "Introduction to Algorithms 2ED" textbook by Cormen/Leiserson/Rivest/Stein. It's not starred, so should be fairly easy, but I just can't come up with a closed form solution! The problem is: Suppose that...
  27. C

    I need the final velocity of two balls

    m1 = 5, v1i = +10 m2 = 3, v2i = 0 +y |_+x How do I find v1f and v2f? The balls crash into each other and after the crash I want to know the final velocity.
  28. G

    Discover the Excitement of Rubber Bouncing Balls in Orbit - Shop Now!

    Is it possible to have many rubber bouncing balls (7?) and send it into orbit?
  29. P

    Two Insulated Balls: What is the length of each string?

    Homework Statement Two insulated balls of mass 0.1 g hang from the same support point by massless insulating threads of length l (as shown in the diagram below. A total positive charge of 8.25 × 10-7 C is added to the system. Half this charge is taken up by each ball, distributed uniformly...
  30. S

    What is the upward velocity of a tennis ball after bouncing off a volleyball?

    Homework Statement A 0.25kg tennis ball is placed right on top of a 1kg volleyball and dropped. Both balls hit the ground at a speed of 3 m/s simultaneously. Find the (upward) velocity of the tennis ball right after it bounces up from the volleyball. Assume elastic collisions. (HINT: the...
  31. H

    Do Balls X and Y Conserve Momentum and Energy in an Elastic Collision?

    Two balls X and Y collide elastically. Their speeds before and after collision are as shown. Before After Which of the following equations is correct? A Ux +Uy = Vx +Vy B Ux +Uy = Vx - Vy C Ux - Uy = Vx +Vy D Ux - Uy = Vx - Vy
  32. A

    Video object tracking: ping-pong balls

    I'm interested in determining the trajectory and spin of a ping-pong ball for a project for class. I plan on getting a decent resolution video camera and record the ball (with the camera stationary). Afterward, I'll analyze the video on my computer. My question is: what kind of algorithm can I...
  33. R

    Proving the Openness of Neighborhoods in \Re with Metric \rho(x,y) = |x-y|

    Homework Statement Consider \Re with metric \rho (x,y) = |x-y|. Verify for all x \in \Re and for any \epsilon > 0, (x-\epsilon, x+\epsilon) is an open neighborhood for x. Homework Equations Neighborhood/Ball of p is a set N[SIZE="1"]r(p) consisting of all q s.t. d(p,q)<r for some r>0...
  34. R

    Does the Proof Verify that an Open Ball is a Neighborhood in Metric Spaces?

    First of all, sorry if the notation is hard to read, I'm still getting used to this text entry. Question: Consider \Re with metric \rho (x,y) = |x-y|. Verify for all x \in \Re and for any \epsilon > 0, (x-\epsilon, x+\epsilon) is an open neighborhood for x. Relevant Definitions...
  35. M

    Collision of 2 balls of different masses traveling opposite direction

    [SIZE="4"]Question Two small balls A and B have masses 0.5kg and 0.2kg respectively. They are moving towards each other in opposited directions on a smooth horizontal table when they collide directly. Immediately before the collision, the spped of A is 3m/s and the speed of B is 2m/s. The...
  36. Y

    Electrostatics of balls on a string

    Homework Statement In Fig. 21-42 (I attached an MSPaint rendition of it), two tiny conducting balls of identical mass m and Identical charge q hang from non-conducting threads of length L. Assume \theta is so small that tan \theta can be replaced by its approximate equal, sin \theta. (a)...
  37. B

    How Do You Calculate the Force in Pool Ball Collisions Including Friction?

    I have a bit of time on my hands at the moment and being an avid pool fan I wanted to try my hand at programming a pool simulation. Now I have the balls moving correctly whether they are sliding or rolling but I am having a little trouble getting my head round the collisions. Ideally I want...
  38. V

    What Are the Final Speeds of Billiard Balls After a Perfectly Elastic Collision?

    Homework Statement Two Billiard balls of equal mass undergo a perfectly elastic head on collision (Energy is conserved) . If the speed of one ball was initially at 2.0 m/s and the other 3.0 m/s in the opposite direction, what will be their speeds after the collision?? Homework...
  39. N

    Conceptual question about torque and balls

    [SOLVED] Conceptual question about torque and balls Homework Statement Take a look at the following thread: https://www.physicsforums.com/showthread.php?t=147053 In this thread, the torque is measured from the center of the ball. Can I measure it from the point where the ball and the...
  40. K

    Finding Collision Angles in Pool Ball Refraction

    Hi, I'm currently working on a game of pool/snooker. Its all going great, but i have this problem when the balls hit each other. I can get them to bounce off the walls correctly, but that's because the walls are either vertical or horizontal...hitting a ball is more difficult. At the moment...
  41. S

    Probability of picking one of several balls of one of two colors

    An bag contains four yellow balls and two green balls. Find the probability of getting a yellow ball if you. . . (a) . . . randomly choose a ball from the urn. (b) . . . randomly choose and discard two balls and then choose a third. i know how to do part a..it's just 4/6 = 2/3 but for...
  42. R

    2 balls dropped from a building

    Homework Statement A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof a time of 1.00s later. You may ignore air resistance. If the height of the building is 21.0m, what must the initial speed be of the first ball if both are to hit the...
  43. B

    Two balls falling and bouncing one off the other

    I'm not sure how to do this. The Problem: http://i1.uploadem.com/11052007/untitled.GIF We have two balls one with mass M and another with mass m. M>>>>>m both balls are dropped at the same time, the heavier ball below the lighter ball from a height of 10 meters. (even though the lighter...
  44. C

    Collision between two balls physics problem

    Two identical steel balls, each of mass 4.3 kg, are suspended from strings of length 30 cm so that they touch when in their equilibrium position. We pull one of the balls back until its string makes an angle θ = 65° with the vertical and let it go. It collides elastically with the other ball...
  45. P

    Final question of the day help finding impulse of two billiard balls

    Homework Statement A billiard ball going 4 m/s collides with a stationary ball of equal size cause the second ball to move at an angle of 35 degrees at speed of 2.5 m/s --mass=.3 kg What impulse (magnitude and direction) did second ball receive? What about the first ball? What is the final...
  46. P

    Final speed of two billiard balls

    Both have mass of .5 kg and speed of 2.8 m/s; collide completely inelastically Do I use the conservation of momentum formula? v2= m1/m1 + m2 * v1? Ugh.
  47. C

    Measuring Elasticity of Balls using Collision Method

    This is quite tricky.. How to measure the elasticity of balls using a collision method? apparatus: air track blower gliders motion sensors (2 sets) 2 tennis balls How do i do this?
  48. A

    Solving Collision of Billiard Balls: Speed and Direction

    Homework Statement Similar to the other one... On billiard ball is shot east at 2.6m/s. A second, identical billiard ball is shot west at .8m/s. The balls have a glancing collision, not a head-on collision, deflecting the second ball by 90 degrees and sending it north at 1.58m/s. What...
  49. A

    What torque will bring the balls to a halt in 5.6s?

    Homework Statement A 1.2kg ball and a 2.2kg ball are connected by a 1.0m long rigid, massless rod. The rod is rotating clockwise about its center of mass at 26rpm. What torque will bring the balls to a halt in 5.6s? Homework Equations T = I(alpha) Wf = Wi + alpha (delta t) I =...
  50. B

    Find the Net Force on Ball A from Balls B & C

    Homework Statement Each ball weighs 3.00 kg A is 10cm from C to the left and B is 40cm to the right of A Homework Equations F=Gm1m2/r^2 The Attempt at a Solution ive tried adding the forces that each ball apply to A and subtracting it. i know each has its own force acting on A...
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