Difference between revisions of "Types of Equilibrium"

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A cone balanced on its '''point''' is in a state of '''unstable''' equilibrium. As before, the downward force of the cone's weight, acting through the centre of gravity is balanced by the reaction force of the ground. If the cone is pushed aside - even infinitesimally - the couple created by the two opposing and '''misaligned''' weight and reaction forces  produce '''torque''' twisting the cone even further from the initial position and the cone will swiftly topple. An '''unstable equilibrium''' is more than anything a theoretical curiosity - at best it could only exist as a transient state
 
A cone balanced on its '''point''' is in a state of '''unstable''' equilibrium. As before, the downward force of the cone's weight, acting through the centre of gravity is balanced by the reaction force of the ground. If the cone is pushed aside - even infinitesimally - the couple created by the two opposing and '''misaligned''' weight and reaction forces  produce '''torque''' twisting the cone even further from the initial position and the cone will swiftly topple. An '''unstable equilibrium''' is more than anything a theoretical curiosity - at best it could only exist as a transient state
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'''Neutral equilibrium''' is a special case where no state is more favourable than another e.g. where the cone is lying on it side

Revision as of 12:33, 18 December 2019

Stable, unstable and neutral equilibria

A cone sitting on its base is in a state of stable equilibrium. The downward force of the cone's weight, acting through the centre of gravity is balanced by the reaction force of the ground. The reaction force is equal in size, opposite in direction and perfectly aligned to the weight force. If the cone is pushed aside, the cone's weight still acts through its centre of gravity, but the reaction force is no longer aligned. The reaction now acts at the point of contact between the cone's edge and the ground. The two opposing and misaligned forces create a couple which produces torque tending to twist the cone and can be perceived as the cone "pushing back". Irrespective of which direction the cone is pushed, the reaction force acts to return the cone to the original, equilibrium state, which is why it is termed "stable"

A cone balanced on its point is in a state of unstable equilibrium. As before, the downward force of the cone's weight, acting through the centre of gravity is balanced by the reaction force of the ground. If the cone is pushed aside - even infinitesimally - the couple created by the two opposing and misaligned weight and reaction forces produce torque twisting the cone even further from the initial position and the cone will swiftly topple. An unstable equilibrium is more than anything a theoretical curiosity - at best it could only exist as a transient state

Neutral equilibrium is a special case where no state is more favourable than another e.g. where the cone is lying on it side