newton third law says that action and reaction are equal and opposite but if we throw wet soil on the wall it sticks to wall, it does not returns back, why it happens
Bcz of cohesive forces between the particles of clay
The behavior you observed when wet soil sticks to a wall, instead of bouncing back according to Newton's third law, can be explained by taking into account the forces involved and the nature of the materials.
When wet soil is thrown against a wall, there are several forces at play. First, there is the force exerted by your hand that propels the wet soil forward. This is the "action" force. According to Newton's third law, there is an equal and opposite "reaction" force exerted by the wet soil on your hand.
As the wet soil hits the wall, it experiences another force, which is the normal force exerted by the wall on the wet soil. The normal force is the perpendicular force supporting the weight of an object resting on a surface.
In the case of wet soil sticking to a wall, the force of adhesion comes into play. Adhesion is the force of attraction between molecules of different substances. When wet soil hits the wall, the water in the soil can form adhesive bonds with the wall's surface, causing the soil to stick rather than rebound.
This adhesion force overcomes the force of the wet soil's reaction (which would make it bounce back) due to the difference in the strength of these forces. The adhesive forces between the soil and the wall are larger than the reactive forces trying to push the soil away.
It is important to note that while the adhesion force may be greater than the reactive force in this specific scenario, Newton's third law still holds true. The reactive force is still present, but it is simply overcome by the adhesive forces causing the wet soil to stick to the wall.