The following simulation show a ball bouncing off the ground.
The ratio of velocity after bouncing to velocity before bouncing is eta.
i.e. vy'=eta *vy; (eta=0.95 as default)

The momentum change $\Delta P= m (eta+1)vy$
Assume the friction coeffieient is mu=0.1
The friction between ball and the ground produce momentum change and angular momentum change during bouncing.

/htdocs/ntnujava/ejsuser/2/users/ntnu/fkh/rotateball_pkg/rotateball.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list