Q1. Draw an energy bar chart for each of the following situation. If it matters, write down where the zero of potential gravitational energy is taken to be (without specifying numbers).

1. A car runs out of gas and coast up a hill until finally stopping. Take the system to be car + Earth.
2. A ball starts from rest on the top of one hill, rolls without friction through a valley and just barely makes it to the top of an adjacent hill. Take the system to be ball + Earth. 
3. A brick is held above a spring that is standing on the ground. The brick is released from rest and falls on the spring. A short time later the spring reaches its maximum compression. Take the system to be brick + spring + Earth.