1. PHYSICS FRICTION

2. TOPIC-FRICTION Presentation by group 4 Group members- selena kanhai
Nikeela Maitland
Philip zhu
Marissa ole
TOPIC-FRICTION

3. WHAT IS FRICTION?
Friction is what happens when the surface of any two object rub against each other.
EXAMPLES:
your two hands rubbing together,
your skin rubbing on the snow,
a hammer hitting a nail, or they can be gases,
like friction with the air slowing down your car,
liquids, like friction with the water slowing down a boat.

4. Different Types of Friction
There are four types of friction namely
1.Static friction
2.Kinetic friction
3.Rolling friction
4.Fluid friction

5. WHAT IS STATIC FRICTION?
Static friction is friction between two or more solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface.

6. WHAT IS KINETIC FRICTION?
Kinetic friction is the force that opposes relative motion between surfaces in contact. It is friction applied to a moving object. This is the opposite of static friction, which applies to a non-moving object. A form of friction that opposes the motion of a moving object. (whereas static friction opposes an object that is just about to move, but has not started yet.) Think about sliding a block across a table, the force that pushing the block back against your finger is the force of kinetic friction.

7. WHAT IS ROLLING FRICTION?
Friction is the resistance to the sliding, rolling, or flowing motion of an object due to its contact with another object. Rolling friction is caused primarily by the interference of small indentations formed as one surface rolls over another. This is the idea behind the frictional forces involved with wheels, cylinders, and spheres. In the ideal case of the wheel, we must first look at the forces acting on the wheel. In pure rolling motion friction is required to start, stop, change the motion of a wheel. Below we can see the frictional force necessary to begin motion, and get the wheel moving at a velocity v. In pure rolling motion, friction causes the wheel to catch and stops the sliding and slipping motion; for example when a car spins its tires, slipping is taking place, thus the frictional force works to stop the spinning out and causes the tires to catch and begin pure rolling motion.

8. WHAT IS FLUID FRICTION?
The concepts of fluid friction vary depending on whether the motion is taking place in a liquid or gas. One item that both media share is that the resistance to motion contributes to an object reaching its terminal velocity. This occurs when the resistance from a gas or fluid is equal to the weight of the object, and it remains constant until another force is introduced.
For motion in a liquid, viscous resistance caused by a drag force is proportional to the velocity of the object at slow speeds. This drag force is based on the object's geometry and the viscosity of the liquid, which can vary between fluids. For motion through air, friction at slow speeds is proportional to the velocity. At higher speeds, the drag force depends on the cross-sectional area of an object, the object's density and the drag coefficient. This drag force has a negative value, as the resistance is always opposite the direction of velocity.

9. WHERE IS FRICTION USEFUL?
Whenever an object moves against another object, it feels frictional forces. These forces act in the opposite direction to the movement. Friction makes it harder for things to move.
Helpful frictional forces
friction between our shoes and the floor stop us from slipping
friction between tires and the road stop cars from skidding
friction between the brakes and wheel help bikes and cars slow down
Frictional forces are much smaller on smooth surfaces than on rough surfaces, which is why we slide on ice.

10. WHERE IS FRICTION NUISANCE?
Friction is considered a nuisance when it impedes the desired motion, creates unwanted heat, or damages the moving surfaces. If you are moving a heavy box across a floor, you would find it easier if you could reduce the friction (for example, with a smooth surface or wheels under the box). Automobile bodies are designed to reduce the air resistance that can increase full consumption.
In high-speed aircraft, the airflow around the plane creates significant heat that the plane's exterior materials have to withstand. In the extreme case of the Space Shuttle, the ceramic tiles on its bottom surface resist damage by frictional heat during re-entry.
As seen in shoes and erasers, friction will wear down the surfaces used.

11. HOW CAN WE REDUCE FRICTION?
Polishing Polishing the surface, reduces the irregularities and hence, reduces friction. Lubrication It provides a layer of the lubricant on which the bodies can easily slide. Streamlining Fast cars, boats, planes etc., have a streamlined body. This is to allow air (or water in the case of boats) to easily flow by, without offering much resistance. Use of correct combination of surfaces in contact Use of alloys on moving and sliding parts reduces friction because alloys have a low coefficient of friction.