Moving objects experience friction
When two objects move they both experience a force in the direction that opposes movement- FRICTION.
Friction is a reaction force.
Friction will match the size of the force trying to move the object up to a certain point where there will be less friction and the object can move.
Friction between gripping solid surfaces
This type of friction lets you walk around.
The friction between feet and shoes on the fround allows you to push against it and move forward.
Friction between sliding solid surfaces
E,g, Parts of an engine.
Ways to reduce this:
Use a lubricant like oil or grease.
Drag from fluids
A fluid is a liquid or gas.
An object moving through a fluid has to get past all of the molecules in the fluid whic causes FRICTION.
A big object experiences more resistance than a streamlined object.
Drag only happens in a fluid.