Astronomy Practice Exam

What happens to the gravitational energy of a contracting gas cloud?

1. It decreases

2. It transforms into thermal energy

3. It remains the same

4. It gets absorbed by the environment

The correct answer is: It transforms into thermal energy

When a gas cloud contracts under the influence of gravity, the gravitational potential energy decreases as the particles move closer together. This process converts gravitational energy into thermal energy. As the gas cloud contracts, the particles gain kinetic energy, which translates into increased thermal energy, leading to a rise in temperature within the cloud. This transformation is a key factor in star formation, as the heat generated from gravitational contraction can eventually lead to nuclear fusion once the temperature and pressure in the core become high enough. Thus, the correct answer indicates that the gravitational energy is indeed transformed into thermal energy, highlighting the dynamic relationship between gravitational forces and thermal processes in astrophysical phenomena.