Rolling ball, change of direction

In summary, when exerting lateral forces on a free-rolling ball on a plane with no slipping, the resulting path of the ball will depend on the interaction between friction and gyroscopic effects. If a force is applied from the South, the ball will start rolling to the North and eventually reach a constant speed. If the same force is suddenly applied from the West, the ball's path will change and it may end up rolling in a North-East direction. The apparent axis of rotation may also change from horizontal to eventually North-South, but this is conjecture and further input is needed.
  • #1
jonbarril
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Say I have a magic way to exert lateral forces on a free-rolling ball on a plane, with no slipping. Say I apply a force for a given period from the South, the ball starts rolling to the North and attains a constant speed. Then I suddenly apply the same force for the same period but from the West. What is the resulting path of the ball on the plane? What is the path of the balls apparent axis of rotation (how does it change from East-West to eventually North-South, does it remain horizontal)?

Thanks
--jon
 
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  • #2
If you apply just a force at the ball's CoM, and it starts rolling, the you must have friction. If you then apply the lateral force you will have an interaction of friction gyroscopic effects, which can get quite complex and counter intuitive:

 
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  • #3
Forces are associated to accelerations.
How do you believe the trajectory will change?
 
  • #4
It has been a long while since I took physics. I think the gyroscopic effect will work in favor of helping to turn the ball to the East. My guess is that the ball would end up rolling North-East. Not sure if the axis of rotation would stay flat. This is all complete conjecture. I'm hoping folks out there can give a more informed description of the ball's motion.
 

1. How does the change in direction of a rolling ball affect its speed?

When a rolling ball changes direction, its speed remains constant as long as there is no external force acting on it. This is due to the law of inertia, which states that an object in motion will continue to move at a constant speed and in a straight line unless acted upon by an external force.

2. What factors can cause a rolling ball to change direction?

A rolling ball can change direction due to various factors, such as a change in the slope or surface it is rolling on, a collision with another object, or the application of external forces such as friction or gravity.

3. How does the shape of a rolling ball affect its change of direction?

The shape of a rolling ball can greatly influence its change of direction. A round and symmetrical ball will roll in a straight line, while a ball with an irregular shape or weight distribution may experience more frequent changes in direction due to imbalances in its motion.

4. Can a rolling ball change direction without losing any speed?

Yes, a rolling ball can change direction without losing any speed if there is no external force acting on it. This is known as a perfectly elastic collision, where the ball bounces off another object without losing any kinetic energy.

5. How does the surface on which a ball is rolling affect its change of direction?

The surface on which a ball is rolling can greatly impact its change of direction. A rough or uneven surface can cause the ball to change direction more frequently, while a smooth and even surface will allow the ball to roll in a straight line for a longer distance without changing direction.

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