Understanding Motion: Key Terms
In linear motion, it is essential to understand the following concepts:
- Displacement: This is the shortest distance from the initial to the final position of an object, including direction. It can be positive or negative depending on the direction.
- Distance: This is the total length of the path traveled by an object, regardless of direction. Distance is always positive.
- Speed: This is the rate at which an object covers distance. It is a scalar quantity and is calculated as speed = distance/time.
- Velocity: This is the rate of change of displacement. It is a vector quantity and is given by velocity = displacement/time.
- Acceleration: This is the rate of change of velocity over time, calculated as acceleration = (final velocity - initial velocity)/time.
To distinguish between these terms, remember:
- Distance vs. Displacement: Distance is path-dependent while displacement is path-independent.
- Speed vs. Velocity: Speed does not have a direction, while velocity does.
Key points to remember
- Displacement is the shortest path with direction.
- Distance is the total path length, always positive.
- Speed is distance covered over time, a scalar.
- Velocity is displacement over time, a vector.
- Acceleration is change in velocity over time.
Worked example
Define distance and displacement.
- Distance is the total path length traveled, e.g., 10 km.
- Displacement is the shortest distance from start to end, e.g., 8 km east.