Can a Satellite in Orbit be Considered 'Free-Falling'?

📌 CONCEPT: A satellite in orbit can be considered as 'free-falling' because it is constantly falling towards the Earth due to gravity, but its motion is circular and centripetal, preventing it from actually reaching the ground.

📐 RULE / FORMULA: The concept of gravitational potential energy (U) is crucial here, where U = mgh, and the satellite is in a state of constant free-fall, but its velocity is constantly changing due to the centripetal force.

💡 WORKED EXAMPLE: A satellite of mass 1000 kg is orbiting the Earth at a height of 200 km above the surface. If the acceleration due to gravity is 9.8 m/s^2, we can calculate its gravitational potential energy as U = 1000 * 9.8 * 200,000. Since the satellite is in a state of free-fall, its potential energy is constantly decreasing, but its velocity is constantly changing due to the centripetal force.

⚠️ COMMON MISTAKE: Students often confuse free-falling with the satellite's velocity being zero, when in fact, the satellite is constantly falling towards the Earth, but its velocity is not zero due to the centripetal force.