Frictionless body on Earth's Surface

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Homework Help Overview

The discussion revolves around the behavior of a frictionless body placed on the Earth's surface, particularly focusing on its movement, path, and acceleration under various forces such as gravity, Coriolis, and centripetal forces.

Discussion Character

  • Conceptual clarification, Assumption checking, Exploratory

Approaches and Questions Raised

  • Participants explore the implications of a frictionless body on Earth, questioning the effects of initial velocity and external reference frames. There is discussion about the forces acting on the body, including gravity and normal forces, and how they might interact. Some participants suggest considering the Earth's shape and the behavior of fluids as examples of frictionless motion.

Discussion Status

The conversation is ongoing, with participants raising various considerations and examples related to frictionless motion. Some have suggested specific scenarios, such as the behavior of mag-lev trains and fluids, while others are questioning the assumptions made about the forces involved.

Contextual Notes

Participants note the need to consider the Earth's shape and the nature of frictionless objects, as well as the potential effects of rotational forces on stationary objects.

DBirk
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Homework Statement


Will a frictionless body placed on the Earth move, and if so, describe it's path and acceleration.

Homework Equations


I was given no equations, but I believe that coriolis and centripetal forces would act on the body.

The Attempt at a Solution


I assume that we have to assume an initial velocity of 0 relative to the earth. However, from an external reference frame, the body would appear to be moving as a point on the earth. At the equator this would be approx 1040 mph. However, at latitude angle φ this would decrease as you move towards a pole to cosφ.
The coriolis acceleration, centripetal acceleration, gravity and a force normal to the Earth's surface would act on the body. I assume that gravity and the force normal to the Surface would cancel each other out, but I am not certain. I am having trouble identifying an equation that would capture all of these forces on the body.
 
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You need to allow for the actual shape of tne Earth, i.e. not as a sphere.
Or just consider an object that exists on the Earth's surface and does behave pretty much as frictionless. Can you think of anything?
 
I can only think of fluids as such, water and atmosphere. Those have different behaviors though.
One man-made object that approaches frictionless would be a mag-lev train.
Similar question, would a mag-lev be (slowly) induced into movement by coriolis or other rotational Earth force if it was left stationary?
 
DBirk said:
I can only think of fluids as such, water and atmosphere. Those have different behaviors though.
One man-made object that approaches frictionless would be a mag-lev train.
Similar question, would a mag-lev be (slowly) induced into movement by coriolis or other rotational Earth force if it was left stationary?
I was thinking of a boat.
 

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