Summary
Motion involves understanding how objects move and the forces that affect them. Scalars have magnitude only, while vectors have both magnitude and direction.
- Scalar Quantity — A quantity with magnitude only, no direction. Example: Speed is a scalar quantity as it only has magnitude.
- Vector Quantity — A quantity with both magnitude and direction. Example: Velocity is a vector as it includes direction.
- Speed — Distance travelled per unit time, a scalar quantity. Example: A car moving at 60 km/h.
- Velocity — Change of displacement per unit time, a vector quantity. Example: A car moving north at 60 km/h.
- Acceleration — Rate of change of velocity. Example: A car increasing its speed from 0 to 60 km/h in 10 seconds.
- Deceleration — A decrease or negative change in speed or velocity. Example: A car slowing down from 60 km/h to a stop.
- Speed-Time Graph — Graph showing speed over time; gradient indicates acceleration. Example: A horizontal line indicates constant speed.
- Distance-Time Graph — Graph showing distance over time; gradient indicates velocity. Example: A steep line indicates fast speed.
Exam Tips
Key Definitions to Remember
- Scalar Quantity: Magnitude only, no direction.
- Vector Quantity: Magnitude and direction.
- Speed: Distance per unit time.
- Velocity: Displacement per unit time.
- Acceleration: Rate of change of velocity.
Common Confusions
- Mixing up speed and velocity; remember velocity includes direction.
- Confusing acceleration with speed; acceleration is the change in speed.
Typical Exam Questions
- What is the difference between speed and velocity? Speed is scalar, velocity is vector.
- How do you calculate acceleration from a speed-time graph? Use the gradient of the graph.
- What does a horizontal line on a distance-time graph represent? The object is stationary.
What Examiners Usually Test
- Understanding of scalar vs vector quantities.
- Ability to interpret graphs related to motion.
- Calculating speed, velocity, and acceleration from given data.
