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About the dynamic friction coefficient
I set the dynamic friction to 1 for my physic material of a ball and a cube track. But when the ball is moving along the surface of the cube it's obvious that the dynamic friction coefficient is less than 1.
Answer by Kavorka · Apr 19, 2014 at 05:26 PM
I think you are confusing friction and drag. Friction is enegy loss during sliding contact. The ball moves with rolling contact (mostly).
Well I am okay with my physics I can assure you that. So let's say how can I control the energy lost due to friction? The only way I can see is changing the "Dynamic Friction" value ranged from 0 to 1.I thought that's the dynamic friction coefficient.Tell me whether I have made it wrong or sth. The cube track length is 4 and the initial velocity of the ball is 14.As far as I expected from calculation, after moving from one side to the other side the velocity of the ball should be less than 11. The fact is I saw the velocity of the ball is still more than 12.
Show me your calculation, including constraints and assumptions.
Well just then I found sth new. If I set v1 to 8, the ball can't even roll through a length of 4 before stopped. since 8*8*0.5 is more than 4*9.81 this shouldn't happen
Good. That would be correct if the ball was not rotating. You have correctly accounted for the translational energies.
If the ball rotates you also have to include the ball´s rotational energy which is 1/2*I*w^2. Where I is the ball´s moment of inertia = 2/5mr^2. w is the ball´s angular welocity in radians per second.
What are the ball´s angular velocities at the start and end of the cube track? How much of s is gliding contact and how much of s is rolling contact? Is the cube track horisontal and straight?