Study Notes
Non-uniform motion involves forces that oppose the motion of objects, such as drag forces, which vary with speed and object shape.
- Drag Forces — forces that oppose the motion of an object through a fluid. Example: Friction and air resistance are common drag forces.
- Air Resistance — a specific type of drag force experienced by objects moving through air. Example: Air resistance is more significant at higher speeds, like when cycling fast.
- Terminal Velocity — the constant speed reached when the drag force equals the gravitational force. Example: A skydiver reaches terminal velocity when they stop accelerating during free fall.
Exam Tips
Key Definitions to Remember
- Drag forces are forces that oppose motion through a fluid.
- Air resistance is a type of drag force occurring in air.
- Terminal velocity is the constant speed when drag equals gravitational force.
Common Confusions
- Confusing drag forces with friction in non-fluid environments.
- Misunderstanding that air resistance is negligible at low speeds.
Typical Exam Questions
- What happens to drag forces as speed increases? They increase with speed.
- How does air resistance affect a skydiver? It increases until it balances gravity, leading to terminal velocity.
- What is terminal velocity? It's the constant speed when drag force equals gravitational force.
What Examiners Usually Test
- Understanding of how drag forces vary with speed.
- Ability to explain terminal velocity using Newton's Second Law.