The law of conservation of linear momentum states that in any system of colliding objects the total momentum is always conserved provided that there is no net external force acting on the system.
Secondly
If two or more bodies collide in a closed system,the total momentum after the collision is equal to the total momentum before the collision
Thirdly,
The total momentum of an isolated or closed system of colliding bodies remains constant
The force on the layer will be equivalent to the weight of water on it. This is given by: F = mg; m is the mass of water and g is the acceleration due to gravity.
