Q1: Satellites burn off during re-entry to earth's atmosphere, because of the

ANS:C - friction with earth's atmosphere.

Satellites burn off during re-entry to Earth's atmosphere primarily due to friction with Earth's atmosphere. Explanation:

1. Friction with Earth's Atmosphere: When a satellite re-enters Earth's atmosphere, it encounters the dense air molecules in the atmosphere at high speeds. These air molecules create friction with the surface of the satellite, causing intense heating. The high-speed frictional interaction generates tremendous heat, which can lead to the heating and burning of the satellite's surface materials. This phenomenon is often referred to as atmospheric re-entry heating or aerodynamic heating.
2. Combustion with Air: While the frictional heating during re-entry can cause materials on the satellite's surface to burn, it is not a combustion process with air in the traditional sense. Instead, it is primarily a result of the intense heat generated by friction with the atmosphere.
3. Gravitational Pull by Earth: Although Earth's gravitational pull plays a role in the re-entry process by causing the satellite to accelerate towards Earth, it is not the primary reason for the burning of the satellite during re-entry.
4. Loss in Weight of the Satellite: The loss in weight of the satellite during re-entry is not a direct cause of the burning phenomenon. Instead, it is a consequence of the aerodynamic forces and heating experienced by the satellite as it descends through Earth's atmosphere.