Mechanical Engineering - Engineering Mechanics - Discussion

Well it simple cause the surface of that is talk about is the convex surface and it is not a plane nor smooth surface. And therefore the cylinder cannot be stable.

It has to be neutral because even when it is disturbed - it's centre of gravity remains at the same position. Similar to a cone resting on it's side.

Convex lens has no friction, and also smooth cylinder has friction too. Then the body will moving downward. Then that is unstable.

@Manali.

If force is zero then by 1st law of newtons, it will remain stationary or in motion until unless applied any external force on it so due to this it must be in stable position.

Or one reason more, force is zero then it will be in equilibrium because if we will consider all forces then it should be in equal and opposite hence it also must be in stable position.

1. An equilibrium is considered stable if the system returns to it after small disturbances.

2. If the system moves away from the equilibrium after small disturbances, then the equilibrium is unstable, and.

3. The neutral equilibrium is that when moved slightly, it neither tends to return to its former position not depart more widely from it.

So 2nd option best fits, :).

At the convex surface though it is a smooth body tends to slides. Hence, unstable.

Convex means it lies on horizontal position without friction force since it is given as smooth surface. So here cg lies above meta center so unstable.

Why is not in stable?

It should be neutral equilibrium. Equilibrium has three types: stable, unstable and neutral. Stable equilibrium is the condition when a small disturbance is given it try to come into the original position.

In case of unstable equilibrium object will never come into equilibrium position when given a small disturbance. Neutral equilibrium is the condition when object comes to a new equilibrium condition when given a small disturbance. This is is the third case.

Surface is smooth so no friction, due to no friction no force apply on the cylinder to stop rolling, it's continuous rolling inside the convex surface.