I have a project in university. it is a simulation of soccer kick so I created all the forces like magnus and drag and friction and gravity and so on.. now the ball is moving and has a linear velocity and angular velocity. I know that the linear velocity will decrease because of the friction, but how the angular velocity will decrease. what torques effect the ball while it is moving and spinning.

  • $\begingroup$ a lot of people seem to have a similar project recently... $\endgroup$ Commented Jul 3, 2021 at 23:07
  • $\begingroup$ @JohnHunter Oh I wasn't aware of this. Should I delete my answer? $\endgroup$
    – noah
    Commented Jul 3, 2021 at 23:43
  • $\begingroup$ It could be worth a search of recent questions with "ball" or "soccer" in them $\endgroup$ Commented Jul 3, 2021 at 23:45
  • $\begingroup$ @noah , sorry thought you were the questioner, it's up to you after you've searched, perhaps you will know what's best... $\endgroup$ Commented Jul 3, 2021 at 23:46
  • $\begingroup$ @JohnHunter I have only found two related questions in relatively recent time, both asking for differet concepts and both asked by the same user. I'll leave the answer here but will holf off on elaborating on exact calculations in case this is some kind of problem sheet. $\endgroup$
    – noah
    Commented Jul 3, 2021 at 23:48

1 Answer 1


It's really very much the same as for linear velocity, i.e. friction with the air. Since the frictional force opposes the velocity of the surface, a spinning ball experiences a torque opposing its rotation from its surface rubbing against the air around it.

  • $\begingroup$ thank you for answering . how can i calulate the torque exactly $\endgroup$ Commented Jul 3, 2021 at 22:59
  • $\begingroup$ the magnus effect comes from this torque (the fact that air resistance is greater on one side of th ball than the other). look up forces in the mangus effect and that should help get you in the right direction @ahmadalseirafi $\endgroup$
    – Señor O
    Commented Jul 3, 2021 at 23:39

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