ASVAB (Armed Services Vocational Aptitude Battery)General Science (GS)Hard
A satellite orbits Earth at a constant speed, but its velocity is continuously changing. This phenomenon occurs because:
- Athe gravitational force from Earth is not uniform.
- Bthe satellite's mass is decreasing due to fuel consumption.
- Cthe satellite is experiencing air resistance.
- Dthe satellite is continuously changing direction.
Show answer & explanationAnswer & explanation
Correct answer: D. the satellite is continuously changing direction.
Velocity is a vector quantity, meaning it has both magnitude (speed) and direction. Even if an object's speed is constant, if its direction of motion is continuously changing (as in circular or orbital motion), its velocity is changing, implying acceleration.
Why the other options are wrong
- A. Gravitational force from Earth is effectively uniform enough to cause continuous direction change in orbit.
- B. While mass might decrease, this doesn't explain constant speed with changing velocity. Velocity changes due to direction.
- C. Satellites in stable orbits are typically in space with negligible air resistance.
Velocity vs. Speed
Speed is the rate at which an object is moving (magnitude), while velocity is the rate at which an object is moving in a specific direction (magnitude and direction).
- Velocity is a vector quantity; speed is a scalar quantity.
- An object can have constant speed but changing velocity if its direction changes.
- Changing velocity means there is acceleration.
Memory trick: Speed is just how fast, Velocity adds the path, Acceleration changes both.