Can spin result in an increase of velocity?

  • Context: Undergrad 
  • Thread starter Thread starter d1v1n1ty nb
  • Start date Start date
  • Tags Tags
    increase Spin Velocity
Click For Summary

Discussion Overview

The discussion centers around the question of whether a spinning ball can increase its velocity in the direction of travel upon impact with a surface. Participants explore various scenarios, equations, and principles related to this concept, including the effects of spin, angular momentum, and energy conservation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant queries the possibility of a spinning ball increasing its velocity upon hitting the floor and requests examples and equations.
  • Another participant suggests that a rubber ball can exhibit complex behavior, such as bouncing back and forth while changing direction of spin and motion, though acknowledges the difficulty in calculating this behavior due to the need for proper data and assumptions.
  • A third participant recommends drawing a free body diagram (FBD) and applying the equations of motion, specifically mentioning the concept of a "slam" in ping pong.
  • Another participant points out the challenges in calculating the forces involved, noting that the force varies and is dependent on specific properties of the objects involved, suggesting that a fraction of angular momentum could convert to linear momentum based on elastic modulus.
  • One participant introduces the idea of conservation of energy, arguing that if the impact reduces the spin, the energy lost from rotation could be converted into linear kinetic energy.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of how spin affects velocity upon impact, with no consensus reached on the specific conditions or outcomes involved in this scenario.

Contextual Notes

The discussion highlights limitations related to the variability of forces during impact, the dependence on material properties, and the challenges in quantifying the interactions involved.

Who May Find This Useful

This discussion may be of interest to those studying mechanics, particularly in the context of sports physics, material properties, and energy transfer in collisions.

d1v1n1ty nb
Messages
5
Reaction score
0
If a spinning ball hits the floor is it possible for it to increase in velocity in the direction it is travelling? If so could you please explain with an example? And what Equations would you use? Thanx.
 
Physics news on Phys.org
Absolutely - you can do all sorts of crazy things with a rubber ball. If you bounce it from the ground to a wall at a low angle (throw it near the corner), you can even get it to bounce back and forth as its direction of spin and direction of motion both reverse every time it hits the ground.

It may be difficult to caluclate (or rather, difficult to get proper data/assumptions), but you could use angular momentum converted to linear momentum.
 
Draw a FBD of the ball in contact with the surface, including friction.
Then just apply f=ma and T=I alpha.
It is called a slam in ping pong.
 
That would be difficult because the force varies and you don't know things like time of contact. It is very dependent on many specific properties of the objects. I was thinking that given a certain elastic modulous, a specific fraction of the angular momentum would be converted to linear momentum.
 
But you can argue "conservation of energy". If the impact reduces the spin, then the energy due to rotation is reduced and can go into linear kinetic energy.
 

Similar threads

  • · Replies 60 ·
3
Replies
60
Views
7K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 10 ·
Replies
10
Views
5K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 39 ·
2
Replies
39
Views
4K
  • · Replies 5 ·
Replies
5
Views
4K