Speed, velocity and acceleration
Speed, Velocity and Acceleration
Speed
- Speed is the measure of how quickly an object moves.
- It is a scalar quantity, meaning it has magnitude but no direction.
- The unit of speed is metres per second (m/s) but it can also be expressed in km/h or mph.
- Calculating speed involves using the formula: speed = distance / time
Velocity
- Velocity, on the other hand, is speed in a given direction.
- It is a vector quantity, meaning it has both magnitude and direction.
- Therefore, if an object changes direction but keeps the same speed, its velocity has changed.
- Just like speed, velocity uses the unit metre per second (m/s).
Acceleration
- Acceleration is the rate of change of velocity of an object.
- An object can be accelerating if it is speeding up, slowing down, or changing direction.
- It is a vector quantity, which means it has both speed and direction.
- The unit for acceleration is metres per second squared (m/s²).
- Calculating acceleration involves using the formula: acceleration = change in velocity / time taken
- If an object is slowing down rather than speeding up, we say it has negative acceleration, which is also known as deceleration.
Relationship between Speed, Velocity and Acceleration
- The speed of an accelerating object increases over time.
- If the velocity of an object changes, whether in magnitude or direction, it is accelerating.
- Understanding the difference between speed and velocity can help explain why objects moving at constant speed can still experience acceleration - it’s because their direction is changing.
- All three: speed, velocity, and acceleration are fundamental to understanding the principles of force and motion.