Physics for IGCSE & O level - Forces And Pressure (Section 5 - No. 16)
What are the two necessary conditions for an object to be in equilibrium?
The sum of forces must be zero.
The sum of moments must be zero.
The object must be stationary.
The object must be moving at a constant speed.
Forklaring
For equilibrium, both the net force and the net moment must be zero.