A mass with M = 122kg is attached to the bottom of a block-and-tackle pulley system.How much tension force is needed to keep the mass at its current position?

Answer 1

The answer depends upon the amount of friction and the number of ropes and blocks in the block and tackle system.

See
http://science.howstuffworks.com/transport/engines-equipment/pulley.htm

In an ideal systen with one block, the answer would be half the weight of the mass.