1. A gas in a closed container is heated, causing the lid of the container to rise.
The gas performs 6J of work to raise the lid, such that is has a final total energy
of 18J. How much heat energy was added to the system?

2. A gas in a closed container is heated with 70J of energy, causing the lid of the
container to rise. If the change in energy of the system is 35J, how much work
was done by the system?