The Nearest Asteroid · Physics Brawl 2020 #FoL.4
Physics · mechanics
Problem
On 16th August 2020, an asteroid (later called 2020 QG) has been recorded as the closest asteroid (spotted so far) that flew by the Earth without colliding with it. At the nearest point of approach, it was only 2950km above Earth's surface and it had a velocity . How much higher was its velocity compared to the escape velocity at that height above Earth's surface? Find the ratio .Intuitive explanation
This problem tests whether you understand the relationship between an object's orbital speed and escape velocity at a given height. The key insight is that escape velocity depends only on the distance from Earth's center and the planet's mass—it's not about the asteroid's trajectory, just the gravitational potential at that location. Calculate using the standard formula at the asteroid's distance, then simply divide the given velocity by it to find how much faster the asteroid was moving relative to the escape threshold.
Intuitive explanation
This problem tests whether you understand the relationship between an object's orbital speed and escape velocity at a given height. The key insight is that escape velocity depends only on the distance from Earth's center and the planet's mass—it's not about the asteroid's trajectory, just the gravitational potential at that location. Calculate using the standard formula at the asteroid's distance, then simply divide the given velocity by it to find how much faster the asteroid was moving relative to the escape threshold.