Why are most elected members only elected for 5 years and not for life time?

It is because Citizens cold observe the developments taken place and if they think that the ruling party is not working properly, the election after every 5 years give them the chance to choose a better representative.It gives people to change their choice of choosing the right representative.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.