# Calculating Friction due to rotation from ball bounce? [duplicate]

In this question asked by codemonkey, The rotation will depend upon:

upon impact, on:

• Initial Speed of the ball hitting the surface (magnitude of ball velocity vector)
• Friction co-efficient of ball & surface (constants for simulation)
• Angle between ball impact velocity vector and the surface normal

Everything is fine except for second point. How the friction coefficient of ball and surface should be taken into account? EDIT: The problem with my approach is i donot know the impact time of the collision. If say the time of impact is dt, Vn1 is the final velocity parallel to the surface then

mass*(Vn1-Vn0)/dt X r = torque


Then i can calculate the angular velocity produced by this torque if it acts for dt time.

also

Vn1= Vn0 + accelaration* dt


where

accelaration+angular_accelaration*r


Please correct me if i am wrong. Also how do i calculate dt?

• With zero friction, the ball would not rotate at all. The coefficients of friction will be used to calculate if there is any slippage, thus reducing the amount of rotation added to the ball and reducing the energy of the ball. The correct way to handle a question that's already been asked, but has incomplete answers is to apply a bounty to the original question, explaining that you'd like more complete answers. Feb 3, 2014 at 15:04