GED Science TestPhysical ScienceMedium
A satellite is orbiting the Earth at a constant speed in a circular path. Although its speed is constant, the satellite is continuously accelerating. Which force is responsible for this constant acceleration?
- AGravitational force
- BAtmospheric drag
- CElectromagnetic force
- DThrust force from rockets
Show answer & explanationAnswer & explanation
Correct answer: A. Gravitational force
Acceleration is a change in velocity, which can be a change in speed or direction. For an object in circular motion at constant speed, its direction is continuously changing, meaning it is accelerating. This acceleration, known as centripetal acceleration, is directed towards the center of the circle and is caused by the gravitational force between the Earth and the satellite.
Why the other options are wrong
- B. Atmospheric drag would slow the satellite down and cause its orbit to decay, not maintain it.
- C. Electromagnetic forces are not the primary force responsible for orbital mechanics between a planet and a satellite.
- D. Thrust forces are used to change orbit or speed, not maintain constant circular motion.
Centripetal Force in Orbit
For an object in a circular orbit, the centripetal force, which causes the object to continuously accelerate towards the center of its path, is provided by the gravitational attraction between the orbiting body and the central body.
- Centripetal force is always directed towards the center of the circular path.
- It causes a change in direction of velocity, not necessarily speed.
- For satellites, gravity is the centripetal force.
Memory trick: Satellites 'Gravitate' to the center, constantly turning.