Whenever one object exerts a force on a second object, the second object will exert an equal and opposite force on the first object.
In order for this law to work, you must have two separate forces, and two different objects. This law says that when one object applies force to another, the other object will push back in the opposite direction or the first object. Friction is an example of this law. If you have a block, and you put it on a table, the weight of the block will be pushing dow