IB Physics Flashcards: Kinematics
IB Physics — Kinematics Flashcard Deck
Flashcards with spaced repetition. Press Space to flip, then rate your recall (1—4).
Key Concepts
SUVAT Equations describe motion under constant acceleration. The five variables are displacement (s), initial velocity (u), final velocity (v), acceleration (a), and time (t). Each equation links four of these five variables and is used when acceleration is uniform. The four equations are: v = u + at, s = ut + ½at², v² = u² + 2as, and s = ½(u+v)t. For example, v² = u² + 2as is useful when time is not given. These equations only work for constant acceleration — if acceleration varies, calculus methods (integration of acceleration to find velocity, integration of velocity to find displacement) are required.
Projectile Motion can be split into independent horizontal and vertical components. The horizontal component has constant velocity (no air resistance assumed), while the vertical component has constant acceleration due to gravity (g ≈ 9.81 m/s² downward). The trajectory is always a parabola. Key insight: the horizontal and vertical motions are independent — you can analyse each separately and combine results. For a projectile launched at angle θ with speed v₀: horizontal component = v₀cosθ, vertical component = v₀sinθ.
Terminal Velocity occurs when the drag force on a falling object equals its weight. The net force becomes zero, so acceleration drops to zero and the object falls at a constant speed. This is why skydivers reach a steady speed before opening their parachute. The process: initially, weight > drag, so the object accelerates. As speed increases, drag increases (drag ∝ v²). Eventually drag = weight, and the object reaches terminal velocity. Opening the parachute dramatically increases drag, causing deceleration until a new, lower terminal velocity is reached.
Displacement-Time vs Velocity-Time Graphs: The gradient of a displacement-time graph gives velocity; the gradient of a velocity-time graph gives acceleration. The area under a velocity-time graph gives displacement. For uniform acceleration, the velocity-time graph is a straight line; for non-uniform acceleration, it’s a curve. The area under a curve can be estimated by counting squares or using the trapezium rule.
Intuition
Imagine throwing a ball horizontally off a cliff. The ball moves forward at a steady rate (horizontal velocity is constant) while simultaneously falling faster and faster (vertical velocity increases due to gravity). The combination of these two independent motions creates the curved parabolic path you see. You can analyse each direction separately and then combine the results. Terminal velocity is like a speed limit imposed by air resistance — the skydiver accelerates until air resistance pushes back hard enough to balance gravity.
Why it matters: Kinematics is the foundation of mechanics and is essential for understanding everything from car safety (crash dynamics) to space travel (orbital mechanics). It teaches the fundamental skill of breaking complex motion into simpler components.
Common Pitfalls
- Confusing distance with displacement: distance is a scalar (total path length), while displacement is a vector (straight-line change in position). They differ when the object changes direction. An object that walks in a circle has zero displacement but non-zero distance.
- Forgetting to resolve vectors into components before applying SUVAT equations. You cannot mix horizontal and vertical quantities in the same equation. Always split the initial velocity into horizontal (v₀cosθ) and vertical (v₀sinθ) components first.
- Using g = 10 m/s² when the question specifies 9.81 m/s² (or vice versa). Always check which value the question expects. Using the wrong value introduces a systematic error of about 2%.
- Forgetting that the time of flight is the same for both horizontal and vertical components of projectile motion. This is the key insight that links the two independent motions.
Cross-References
- Mechanics: Mechanics covers forces and energy, which explain WHY objects accelerate — kinematics describes HOW they move.
- Waves: Waves transfer energy, and the kinematics of oscillating particles underlies wave behaviour.
- Nuclear and Quantum: Nuclear physics involves particle motion and energy, and quantum physics describes particle behaviour at atomic scales.
- Electricity: Electric charges move through circuits, and their motion can be described using kinematic concepts.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.