There isn't a strict classification of elastic forces into just two kinds. However, we can broadly categorize them based on their origin and application:

1. Elastic Forces Based on Material Properties:

* Hookean Elasticity: This is the most common type of elasticity. It refers to the force that arises due to the deformation of a material that follows Hooke's Law. Hooke's Law states that the force is directly proportional to the displacement from the equilibrium position. This is observed in springs, rubber bands, and many other materials when they are stretched or compressed within their elastic limit.

2. Elastic Forces Based on Specific Systems:

* Surface Tension: This force originates from the cohesive forces between molecules at the surface of a liquid. It causes the liquid to behave as if it has a stretched elastic membrane on its surface.

* Elasticity in Solids: This covers a wide range of elastic behaviors observed in solids, including Young's Modulus (measuring resistance to stretching), Shear Modulus (measuring resistance to shearing), and Bulk Modulus (measuring resistance to compression).

Important Note:

It's crucial to understand that the "two kinds" concept is a simplified way of looking at elastic forces. There are various other types and complexities depending on the specific system and conditions. For example, there's also the concept of nonlinear elasticity, where the force-displacement relationship is not linear, and viscoelasticity, which combines elastic and viscous properties.