A contact force is a push or pull that is exerted when two or more objects are physically touching. There are several types of contact forces.

• An applied force, where a person or object is pushed or pulled by another object, is one type of contact force. 
• Friction, which is a force exerted on a moving object and opposes the motion of that object, is a contact force.
• When a contact force acts perpendicular to an object, it is called a normal force.  A normal force holds a book on a table.

Of these types of forces, the normal force might be the least familiar to you, but it is everywhere. When you sit on a chair, the chair is holding you up with normal force. Your computer is being held there by the normal force exerted by the table. If you lean against a wall, the wall exerts a normal force on you. If you are building something and are holding a piece of wood in place, you are exerting a normal force on the wood. Your building partner might be exerting an applied force on the nail with a hammer.

Friction is the force that slows a ball down as it rolls across the gymnasium floor.

An applied force is the force of you pushing a door open.

Drag the actions onto the correct forces present in the picture above.