IIT JEE , AIEEE Forum - Physics , Mechanics

kunwardeep

What is the difference between 'Unstable equilibrium' and 'not in equilibrium' ?

aditya_arora04

Hi,

Unstable equilibrium is a condition when the net force on a body is zero, but potential energy of the system is maximum.

Not in equilibrium means that some net force is acting on the body due to which it experiences either a translational motion or rotational motion or both.

kunwardeep

When between 2 similar charged particles, another same charge particle is kept, along the perp. bisector, is it in unstable or not in equilibrium ??

spideyunlimited

not in equilibrium. net component sin@ will push the third particle away.

kunwardeep

But the correct answer given in all books is that it is in unstable equilibrium

akhil_o

Simpleway to find out-
draw a graph of U vs x
wherever dU/dx is 0 there is equilibrium
stable equilibrium is achieved at minima of U and vice versa

ashwin123

Unstable eqiulibrium is when the net force on the body=0 but the body on slight displacement doesnt tend to come back to orignal posn.

Not in eq means net force is non zero

Check the figure.

Assume black thing to be bob. The bob on displacement towards right will go down the wedge straight away. that is unstable eq.

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