1. 1)when a beyblate is spined it spin for longer time with its pointed end rather than its blunt end,friction is independent of area of contact so what might be the logical explanation for its longer spin with pointed end and shoter spin for its blunt end?

2)AND also friction force is the result of electorostatic force in inner level than why it is independent of area of contact? I know we cannot say more the nearrerness between the molecules more is the electrostatic force of attraction resulting more friction but why?

2.

3. I think the trick here is that for a spinning object, a smaller tip means that each point on it has to move less to make one revolution, which gives it more torque and a slower speed, both of which let it overcome friction more easily.

4. sorry i could not get you please make it clear what you want to say.i am not getting any picture through your comment.

5. I'm not sure how to say it more clearly than that. A smaller turning radius means it has to move less to make a turn, so friction would effect it less.

6. The frictional force on any point of the tip is equal to the normal force, divided by the surface area of contact multiplied by the coefficient of friction. The torque slowing down the top is equal to the frictional force multiplied by the length of the lever arm. If the force is all concentrated very close to the center of rotation, the lever arm is very short, so the decelerating torque is small.

7. the tip usually lies on the c.g of beyblates, for the stable circular motion c.g should be at same axis or at same point,so if you want to say tip has to move than it make no sense.n also what about my second question i posted?

8. Originally Posted by saurab dulal
the tip usually lies on the c.g of beyblates, for the stable circular motion c.g should be at same axis or at same point,so if you want to say tip has to move than it make no sense.n also what about my second question i posted?
A point has zero dimension. The tip of a top is not a point - it has a small but non-zero diameter. What about your second question? I answered it.

9. harold 14370wrote:
The frictional force on any point of the tip is equal to the normal force, divided by the surface area of contact multiplied by the coefficient of friction.

i never found anywhere the defination of frictional force as you said. rather i found that frictional force is the component(horizantal) of contact force(the force due to electostatic interaction betwen molecules incontact )and normal force is another component of same contact force.frictional force is equal to normal force multiplied with coefficient of friction.also if i and my refrence book are wrong in about the understanding of friction force then help me where can i find the exact defination like you said.
also about the point, as i know c.g always lies on a point in general defination and in case of top it is on the same vertical axes with tip of top which i called point and i think it doesnt matter whether you call it point or dimensional.your explanation doesnt concern with my question.

10. Originally Posted by saurab dulal
harold 14370wrote:
The frictional force on any point of the tip is equal to the normal force, divided by the surface area of contact multiplied by the coefficient of friction.

i never found anywhere the defination of frictional force as you said. rather i found that frictional force is the component(horizantal) of contact force(the force due to electostatic interaction betwen molecules incontact )and normal force is another component of same contact force.frictional force is equal to normal force multiplied with coefficient of friction.also if i and my refrence book are wrong in about the understanding of friction force then help me where can i find the exact defination like you said.
also about the point, as i know c.g always lies on a point in general defination and in case of top it is on the same vertical axes with tip of top which i called point and i think it doesnt matter whether you call it point or dimensional.your explanation doesnt concern with my question.
I think I stated that wrong about the surface area. The point is that the normal force will be spread out over an area, not a single point. If it were a single point thien the pressure at that point would be infinite. Something has got to give. The material will deform until there is a sufficient area of contact to support the normal force on the tip. Therefore the force counteracting the rotation will be spread out over a circular area of contact and will act as if it were effectively located at some distance from the point of rotation.

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