You can't bounce a ball under a table

Steve Mould

Steve Mould

12 min, 54 sec

The video presents a detailed explanation of the dynamics involved when a ball bounces off surfaces, particularly under a table, and how this phenomenon can be used to explain the golf ball paradox. It uses practical examples, animations, and slow-motion footage to illustrate the principles involved.

Summary

  • The video begins with the observation that a ball tends to bounce back in the same way it came in when tossed under a table, a principle demonstrated by the narrator's friend Hugh Hunt.
  • This principle is also similar to the golf ball paradox presented in an earlier video, a connection the narrator didn't initially make.
  • To simplify the problem, the narrator reduces the golf ball paradox to a ball bouncing between two surfaces, like under a table.
  • He then increases the number of surfaces the ball bounces off, illustrating the point by showing a ball bouncing inside a square container without touching the back wall.
  • The narrator explains that each time the ball hits a surface, it imparts some spin onto the ball, which then affects the direction the ball moves after it hits the next surface.
  • The video concludes with an explanation of the golf ball paradox in terms of continuous rather than discrete collisions, as the number of faces in the container approaches infinity.

Chapter 1

Introduction and Statement of the Problem

0:00 - 29 sec

The narrator introduces the topic and presents the problem of how a ball bounces back in the same way it came in when tossed under a table.

The narrator introduces the topic and presents the problem of how a ball bounces back in the same way it came in when tossed under a table.

  • The narrator begins by observing how a ball tends to bounce back in the same way it came in when tossed under a table.
  • This principle is also similar to the golf ball paradox presented in an earlier video, a connection the narrator didn't initially make.

Chapter 2

Explanation of the Principle Using a Two-Surface Model

0:31 - 1 min, 19 sec

The narrator simplifies the golf ball paradox by reducing it to a ball bouncing between two surfaces, like under a table.

The narrator simplifies the golf ball paradox by reducing it to a ball bouncing between two surfaces, like under a table.

  • To simplify the problem, the narrator reduces the golf ball paradox to a ball bouncing between two surfaces, like under a table.
  • He explains that when the ball hits the ground, the ground imparts some spin onto the ball, which then affects the direction the ball moves after it hits the next surface.

Chapter 3

Extending the Principle to a Square Container

3:28 - 2 min, 4 sec

The narrator extends the principle to a square container, showing how the ball changes direction and spin after each bounce.

The narrator extends the principle to a square container, showing how the ball changes direction and spin after each bounce.

  • The narrator shows a ball bouncing inside a square container without touching the back wall, illustrating how the ball's direction and spin change after each bounce.
  • He explains that as the ball collides with each surface, the surface imparts some spin onto the ball, causing it to change direction.

Chapter 4

Further Extension to an Octagonal Container

5:47 - 2 min, 25 sec

The narrator extends the principle to an octagonal container, explaining how the changes in the ball's direction and spin after each bounce become smaller, but the overall effect remains the same.

The narrator extends the principle to an octagonal container, explaining how the changes in the ball's direction and spin after each bounce become smaller, but the overall effect remains the same.

  • The narrator extends the principle to an octagonal container, showing how the changes in the ball's direction and spin after each bounce become smaller, but the overall effect remains the same.
  • He explains that as the number of surfaces in the container increases, the changes in the ball's direction and spin after each bounce become smaller, but the overall effect remains the same.

Chapter 5

Connecting the Discrete Bounces to the Continuous Golf Ball Paradox

8:14 - 1 min, 25 sec

The narrator explains the golf ball paradox in terms of continuous rather than discrete collisions, as the number of faces in the container approaches infinity.

The narrator explains the golf ball paradox in terms of continuous rather than discrete collisions, as the number of faces in the container approaches infinity.

  • The video concludes with an explanation of the golf ball paradox in terms of continuous rather than discrete collisions, as the number of faces in the container approaches infinity.
  • The narrator explains that as the number of faces in the container approaches infinity, the number of discrete collisions tends towards infinity, resulting in a continuous change in the direction of the spin of the ball as it rolls around the inside of the cylinder.

Chapter 6

Conclusions and Final Thoughts

9:42 - 2 min, 53 sec

The narrator concludes the video by summarizing the main points and discussing related topics such as the concept of angular momentum, the role of friction in changing the ball's trajectory and spin, and the use of discretization in physics. He also promotes Incogni, a service that removes users' data from data broker databases to reduce spam.

The narrator concludes the video by summarizing the main points and discussing related topics such as the concept of angular momentum, the role of friction in changing the ball's trajectory and spin, and the use of discretization in physics. He also promotes Incogni, a service that removes users' data from data broker databases to reduce spam.

  • The narrator concludes the video by summarizing the main points and discussing related topics such as the concept of angular momentum, the role of friction in changing the ball's trajectory and spin, and the use of discretization in physics.
  • He also promotes Incogni, a service that removes users' data from data broker databases to reduce spam.

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