When A weight lifter in holding a weight of 120 kg on his shoulder for 30 s .calculate amount of work done.?

To calculate the work done, we need to know the distance over which the weight lifter held the weight. If we assume the weight lifter held the weight steady at shoulder height (about 1.5 meters), the work done would be Weight x Height = 120 kg x 1.5 m = 180 Joules.