Concept: Friction and Its Types
Friction and its features:
- Friction is a type of contact force.
- When friction occurs, two bodies remain in contact, so friction is a contact force.
- Overall, we can say that friction is a force that comes into play when two surfaces come in contact with each other.
- The force of friction always opposes the motion of an object and reduces its velocity.
- Frictional force always acts from the opposite side of an object’s motion.
- A ball rolling on the floor gradually slows down.
- When we stop pedalling a bicycle, it gradually slows down.
- Dragging a chair on the floor.
Factors affecting friction:
Friction mainly depends on two factors—
- The nature of the surfaces—rough surface or smooth surface.
- If the surface is smooth, the force of friction will be less, and if the surface is rough, the force of friction will be more.
- Friction also depends on how hard the surfaces press together.
Causes of friction:
Friction happens when two rough surfaces come in contact, and due to their irregularities, the frictional force starts to act at the opposite side of the motion.
Types of friction:
Friction can be divided into three types.
1. Static friction:
- It is the type of frictional force that is exerted on an object which is at rest.
- Static frictional force comes into play until an object starts moving.
- A resting object starts moving after overcoming the static friction.
Examples: Pushing any resting object can cause static friction like walking, rock climbing, rubbing hands, etc.
2. Sliding friction:
- Sliding friction comes into play when the surface of an object slides over the surface of another object.
- Sliding friction opposes the sliding movement of another object.
Examples: Sliding on a sledge, playing on a slide, dragging anything from right to left on the floor.
3. Rolling friction:
- Such friction exerts when an object rolls over on a surface.
Examples: Movement of a wheel, the friction between a paint roller and the wall.
4. Fluid friction:
- When an object moves underwater, the fluid exerts friction on the object, called fluid friction.
- To reduce fluid friction, objects should have a streamlined body.
Examples: Fish moving underwater, Underwater submarines.
- When an object moves through the air, the air exerts a resistance force that opposes the object’s motion, which is called air resistance.
- It is also a kind of frictional force.
Examples: Aeroplanes flying, skydiving, paragliding.
Velocity: Speed of an object.
Fluid: A substance that flows.
Streamlined: A body shape that tapers at both ends.
Did You Know?
- The strength of static friction is the highest, and the strength of rolling friction is the lowest.
- The velocity of a static object in reference to other moving objects is called relative motion.