Forces and Friction
- When an object exerts a force on another object, it always experiences a force in return. These two forced can be called an 'interacton pair'.
- That means if you push against a wall, the wall will push back just as hard. As soon as you stop pushing, the wall stops pushing.
- An object resting on a surface experiences a reaction force.
- If a book is on a table , the weight of the book acts downwards, and the table exerts an equal and opposite force upwards on the book.
- The upward force is called a reaction force.
- When an object is moving relatively to another object, both objects experience a force in the direction that opposes the movement-this is friction.
a) Friction between solid surfaces which are gripping.
-This is a kinf of friction that can be found in the Earth's crust-big sections of rock sliding together but friction is forcing them to stay put.
b)Friction between solid surfaces which are sliding past each other.
-You can reduce sliding friction and gripping friction by putting something like oil or grease between the surfaces.
c) Resistance from fluids.
-This is an object moving through a fluid which has to…