Friction force : it acts through the contact between two bodies. It acts along the surface in the direction opposite to the relative speed between the surfaces. It is equal to the coefficient of friction multiplied by the normal force between the surfaces.
Normal force: it is the contact force (it is the push between the two bodies). It acts perpendicular to the surface. If a body is lying on a floor. The body exerts a force equal to its weight on the floor. Floor exerts a force on the bottom surface of the body equal to the weight of the body,
Muscular force , push or pull force or applied force : The force you exert on a door, when you push the door. The applied force can be at any angle.
Spring force, - you have
to pull the string by touching , then
only spring force acts. It is proportional to the extension and opposite to the
direction of extension.
Tension force: It is the
force developed in a string or thread or a thin material, when it is subjected
to a push or pull at its ends. This
force is same all along the thread or rope or string. Tension makes the string
or thread tight. It always acts inward from the ends to the center of the
Air resistance force or drag force : it is proportional to the velocity and is opposite to the movement of the body.
force in a fluid: it is equal to the weight of the fluid displaced by the body. It acts through the surface of the body immersed in a liquid. This is how ships float on water.