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1) When there is no friction , a wheel with a Vcm = X m/s will only be slipping across the surface at a constant velocity.It won't be rotating because there will not be any forces creating torque.

2) The system ( composed of the rotating object ) always tries to find a balance between Rotational and Translational energy so the friction will change direction if Vcm > ωR ( then it will be opposite to the vector of Vcm in order for the rotational energy to be increased) and when Vcm<ωR then the friction will be in the same direction as Vcm , preventing the rotational speed to increase and increasing Vcm instead.

3) So how can a wheel rotate when Vcm = ωR ?? Since no friction is supposed to exist ?!

4) Let's assume that there is a stationary ball of mass M and Radius R on a rough surface(i.e μς=0.1). We give that ball a small push and as a result its centre of mass moves with Vcm = 2m/s.

i) How can we find whether the ball's movements until it stops ? Will it ever stop ? is energy conserved ( if the ball is our system)? What about heat dissipation ?

ii) Won't the static coefficient become smaller ( kinetic coefficient) ? What about that ?

So many questions about this subject which i can't answer one my own so i am asking for your help ! Please do not delete my post again as this isn't a Homework Assignment!

Thank you very much :-)

2) The system ( composed of the rotating object ) always tries to find a balance between Rotational and Translational energy so the friction will change direction if Vcm > ωR ( then it will be opposite to the vector of Vcm in order for the rotational energy to be increased) and when Vcm<ωR then the friction will be in the same direction as Vcm , preventing the rotational speed to increase and increasing Vcm instead.

3) So how can a wheel rotate when Vcm = ωR ?? Since no friction is supposed to exist ?!

4) Let's assume that there is a stationary ball of mass M and Radius R on a rough surface(i.e μς=0.1). We give that ball a small push and as a result its centre of mass moves with Vcm = 2m/s.

i) How can we find whether the ball's movements until it stops ? Will it ever stop ? is energy conserved ( if the ball is our system)? What about heat dissipation ?

ii) Won't the static coefficient become smaller ( kinetic coefficient) ? What about that ?

So many questions about this subject which i can't answer one my own so i am asking for your help ! Please do not delete my post again as this isn't a Homework Assignment!

Thank you very much :-)

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