FRICTION

FRICTION DEFINITION Friction occurs when 2

objects are in contact with each other. The objects apply or exert a force on one another during this time.

Friction acts in the opposite direction of motion – so it is the force that resists movement!

share.ehs.uen.org

FACTORS THAT AFFECT FRICTION

How hard the surfaces push against each other – the more force, the higher the friction

The type of surfaces involved – the smoother the surface, the lower the friction

www.waveequation.com

FRICTION AND SMOOTH SURFACES

Even apparently smooth surfaces actually have microscopic irregularities and bumps. When these come in contact with another surface friction occurs.

www.mrteverett.com

DIRECTION OF FRICTION

Friction acts in the opposite direction of motion, so if the object moves towards the right the frictional force will be towards the left.

www.physics4kids.com

STATIC FRICTION

Definition: The friction that occurs when

objects are not moving. It is the friction that keeps objects in place.

Example: A box sitting on the ground, your

books sitting on a table, your backside against the chair.

HOW TO “OVERCOME” STATIC FRICTION The force needed to

start an object moving must be greater than the static friction.

Reason why a greater force is needed to start an object moving than to continue it moving education-portal.com 

SLIDING FRICTION

Definition: The friction that occurs when 2 solid objects move against each other (or 1 object moves over another)

Example: Bicycle brakes, skinning your knee, walking, writing

USEFULNESS OF SLIDING FRICTION

It can keep you from slipping, sliding and falling (example: sand on an icy road)!

www.goalvanise.com

ROLLING FRICTION

Definition: The friction that occurs when an object

rolls across a surface. Easier to overcome than sliding friction.Example: Anything with wheels (cars,

skateboards) or a ball rolling.

www.school-for-champions.com

ROLLING FRICTION AND ENGINEERS

Engineers use ball bearings to reduce friction – the ball bearings roll between moving parts.

news.thomasnet.com  www.hartfordtechnologies.com

FLUID FRICTION

Definition: The friction that occurs when a solid

objects moves through a fluid. A fluid is a gas or liquid – they flow easily!

Easier to overcome than sliding friction.

Example: Anything moving through the air or

water: riding a bike, surfing, swimming, sky diving

USEFULNESS OF FLUID FRICTION

Parts of machines move more easily when they are oiled.

Fluid friction is what slows down a skydiver when the parachute is opened.