| A | B |
|---|
| friction | the force that resists motion between 2 surfaces in contact |
| if there were no friction | the box would move as soon as you applied any force to it |
| friction between your feet and the ground | allows the action and reaction forces to enable YOU to walk |
| different surfaces | cause different frictional forces |
| when an object is standing still | you need maximum force to overcome friction and start it moving |
| once the object is moving | the frictional force remains constant |
| constant force | is less than the maximum force needed to start the object moving |
| before an object moves, any force less than the maximum | will be balanced by friction and the object will not move. |
| when your force is greater than the maximum | the forces on the object/chair are no longer balanced and begins tomove. |
| the harder 2 surfaces are pushed together | the more difficult it is for the surfaces to slide over each other |
| normal force | is one of the factors that determs how much friction there is |
| the more weight that is applied to an object on the surface | the more friction it has |
| friction between surfaces | produce heat |
| friction causes | individual molecules in an object to move faster and the temperature increases |
| oil is used to | reduce friction in moving machines, otherwise it will overheat |
| air (gases and liquids) | is a fluid |
| fluid | a substance that can flow easily |
| air resistance | is friction due to air |
| the force resisting motion through a fluid | is called a drag |
| friction in fluids | depends on shape of the moving object |
| an object with a larger surface area comes into contact with | more molecules as it moves than an object with a smaller surface area = MORE AIR RESISTANCE |
| the faster an object moves through air | the more molecules it comes into contat with. Speed of object increases = MORE AIR RESISTANCE |
