A contact force, as the name suggests, acts by making direct contact with a point on an object. Contact can be continuous or temporary. In the former case one speaks of continuous force and in the latter case of impulsive force.
Examples:
1) Pushing an object across the ground:
This is an example of a sustained force. Here a continuous direct force is applied to the object to move it along the ground.
2) Kicking a soccer ball:
This is an example of impact force. Here we see that a force is applied to a sphere of a certain mass for a certain time, which causes the sphere to recoil in a certain direction at a certain speed.
Tags:
Physics