A weightlifter holds a 1,000 N barbell 1 meter above the ground. One end of a 2-meter-long chain hangs from the center of the barbell. The chain has a total weight of 700 N. How much work (in ]) is required to lift the barbell to a height of 2 m? What is the average force (average with respect to height of the barbell from the ground) exerted by the weightlifter in the process