Astronomy Practice Exam

What is one possible way for an object to gain or lose orbital energy?

1. Through gravitational potential energy

2. By changing its mass

3. Through friction or atmospheric drag

4. By altering its temperature

The correct answer is: Through friction or atmospheric drag

An object can gain or lose orbital energy primarily through the influence of friction or atmospheric drag. When an object moves within a medium, such as an atmosphere, it experiences resistance that affects its motion. For example, a satellite re-entering the Earth's atmosphere encounters atmospheric drag, which acts as a force against its motion, causing it to lose energy and, consequently, its orbital altitude. This energy loss can result in a faster descent or eventual burning up due to friction with the atmosphere. Conversely, an object can gain orbital energy if it interacts with another body or is propelled by mechanisms such as rocket thrusters. The transfer of energy can lead to changes in its orbit, either increasing its altitude or modifying its velocity. Thus, atmospheric interactions exemplify a significant factor in the gain or loss of orbital energy, illustrating the vital role of drag and friction in orbital mechanics.