Give a short answer for the following question:
 
Define force, mention the force involved in the following cases,

i. A book lying on a table
ii. Pushing a stationary box to make it move.
 
Force is an external effort in the form of push or pull.
 
Force has . So, it is a  quantity.
 
Types of forces depending on the direction in which it acts, they can be classified into two types as:
 
i. , and

 ii.