Tutorial: Using energy bar charts for conservation of energy problems III. Solving problems using energy bar charts. Using the method delineated in this tutorial, solve the following problems. A. Mary's 40 kg brother is at rest on a swing 0.50 m off the ground. Initial and final situation + forces She pulls him up until he is 2.0 m off the ground and releases him. How fast is her brother moving after he passes the bottom and has gone up to 1.5 m off the ground? KE Ugi Usi Wother AEth KEr Ugr Usr