1. Normal force: This is the force exerted by a surface on an object that is in contact with it, acting perpendicular to the surface. When you push a box against a wall, the wall exerts a normal force back on the box, preventing it from moving through the wall.
2. Friction: This force opposes motion between two surfaces in contact. When you push a book across a table, friction acts between the book and the table, slowing down the book's motion.
3. Applied force: This is the force directly applied by an object or person on another object. When you push a door, you are applying an applied force.
4. Tension: This is the force exerted by a stretched string, rope, or cable. When you pull on a rope, the rope exerts a tension force back on your hand.
5. Compression: This is the force exerted by a material that is being squeezed or compressed. When you press on a spring, the spring exerts a compression force back on your finger.
These forces are all contact forces because they require direct contact between objects. They are also reactive forces, meaning they act in response to the applied force.
It's important to note that the specific forces involved and their magnitudes depend on the properties of the objects involved (mass, material, surface properties) and the nature of the interaction (pushing, squeezing, pulling, etc.).
