(455) Fundamentals of motion [IB Physics SL/HL]

Fundamentals of Motion

• Key Concepts Involved:

  • Vectors and Scalars

  • Distance vs Displacement

  • Average and Instantaneous Velocity and Speed

  • Average and Instantaneous Acceleration

Vectors vs Scalars

• Scalars: Quantities with only magnitude (e.g., mass, time, distance, speed).

  • Mass (M): Measured in kilograms.

  • Time (T): Measured in seconds (s).

  • Distance (S): Measured in meters; represents total path traveled.

  • Speed (V): Scalar version; units in meters per second (m/s).

• Vectors: Quantities with both magnitude and direction.

  • Displacement (S): The vector version of distance; indicates position change from start to finish, also measured in meters.

  • Velocity (V): The vector version of speed; includes direction.

  • Acceleration (A): Changes in velocity, measured in meters per second squared (m/s²).

Difference Between Distance and Displacement

• Distance: Total path traveled regardless of direction (e.g., 5 meters in the example).

• Displacement: Straight line from start to finish, considering direction (e.g., 1 meter north).

Average vs Instantaneous

• Average Velocity (v_avg): Change in displacement over total time.

• Average Speed: Total distance traveled over total time.

• Instantaneous Velocity (v_inst): Velocity at a specific point in time.

• Instantaneous Speed: Speed at a specific point in time.

Graphical Representation

• To find instantaneous velocity:

  • Use a tangent line at the point in question to calculate gradient (slope).

Acceleration

• Average Acceleration: Total change in velocity over total time.

• Instantaneous Acceleration: Similar to instantaneous velocity, focus on the gradient of the velocity-time graph.