Why did communism in the soviet union collapse in the late 1980s?

consider:

political factors: what did leaders in the soviet union, the united states, and europe do to further the fall of communism?

military factors: what effect did military policies and actions in the united states and in the soviet union have?

economic factors: what effect did the economic situation in the soviet union have?

social/cultural factors: what was the attitude of the people of the soviet bloc countries? what impact did glasnost have? what was the impact of dissidents?
can anybody me

The Soviet economy was slowly becoming stagnant, whilst military spending went through the roof. Reagan's Strategic Defense Initiative was seen as a threat to be countered, and the Soviets threw more money at the military - the US was spending 15-18% of its Gross Domestic Product (how much the country earns) at the military, the Soviets were spending up to 35% - they were bankrupting themselves. 

To counter this stagnation Gorbachev introduced the policies of Glasnost' and Perestroika (Openness and Re-Structuring) hoping that people would be open about how to rebuild the communist system, and make it work better. All it did was allowed people to openly criticise the system - soon they were calling for it to be replaced. 

Communism was also simply not delivering the promised "workers paradise", wages were stagnant, housing shoddy, cars a rarity, and, from the 1970s they could see the differences between their lifestyle and the West on TV - especially when the (uncensored) Olympics were on. 

Soviet Youth were growing tired of being told that they couldn't see certain films, couldn't listen to Western Music, or listen to Western Radio stations, even wearing jeans were frowned on. Glasnost' allowed them to speak out against the regime - and enabled them to listen to the music they wanted. 

In the Republics, people were tired of being told what to do by Russians, they wanted to govern themselves, or, at least, have more autonomy within the Soviet framework - but the centre would not budge. Because of Glasnost' they could criticise and soon they began to organise. Eventually the people in the Baltic Republics started protesting - demanding independence, and soon, with the collapse of the union, they got it. 

The event that pushed the Soviet Union into the history books was the failed coup of August 1991, when communist hard-liners tried to remove Gorbachev from office, and put in place a more Stalinist system - within two months of this coup the Soviet Union was no more. 

On top of all this was the fact that the party-state elite no longer believed in communism, and saw in capitalism the chance to gain the wealth that they saw their Western contemporaries earn. This elite abandoned any pretence of communism from about 1989 onwards, setting up businesses, banks and taking over the ownership of the enterprises where they worked. 

The capitalist revolution was, in fact, a revolution by the elite, for the elite.