Recent content by Mmarzipan

I'm so trying! Where it touches the ground, r and w are antiparallel. ω is about the vertical axis of the ball. Where the ball touches the ground, r also goes along the vertical axis.

Oh of course! Linear velocity is v=r*ω for any rotation. I'd define r here as distance from the (vertical) axis. But in the point of contact, r is 0. So linear velocity is 0.

I meant that it should slow down the spinning, or shouldn't it? Okie, at the point of the ground angular velocity is practically zero because it's spinning around its vertical axis, shouldn't it be so? , so linear velocity v = (r x ω) * r2. But in the bottom point r and ω are antiparallel so...

Oh, of course! I have no idea how to calculate that tho. The friction force has a different direction at every point, so its torque is against the original spinning, right? so T = dL/dt = I*dw/dt = F*r*sina F being frictional force and r the radius of the sphere. But I have neither of those...

Homework Statement A ball A is rotating on a table with an angular velocity ω about its vertical axis. An identical ball B collides with the ball A elastically. After collision the ball A starts sliding over the table. The coefficient of friction is µ. Find: 1) the angle α between the angular...