A- Gravity. I believe it is gravity since that is the only one that makes sense in this situation. I hope i helped! :)
- "This energy is usually in the form of low-level thermal energy. It is only possible to extract work when there is a temperature difference, so low-level thermal velocity; this means that the force of friction and the applied force are equal in magnitude."
- "An energy transformation is the change of energy from one form to another. Energy transformations occur everywhere every second of the day. There are many different forms of energy such as electrical, thermal, nuclear, mechanical, electromagnetic, sound, and chemical."
