Why were there widespread decolonization efforts and independence movements after world war ii?

Because European metropolises were very fragile after World War II.

Explanation:

During the 19th century, the European powers exhaustively exploited the resources of their colonies, mainly in the African and Asian continents. Nevertheless, some colonies obtained relative development which, in order to continue, required the breaking of colonial ties. The Second World War, in turn, enabled the dominated peoples to discover their own strength, as several of them provided aid to the metropolises during the conflict. European powers were very weak after World War II. These European countries had no economic or political force to combat revolution seeking independence from colonies or decolonization. This European weakness led to the formation of widespread decolonization efforts and independence movements in the colonies.

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."