The SI unit of the rate of change of velocity is meters per second squared (m/s²).
The rate of change of velocity is a fundamental concept in physics and is formally known as acceleration. It measures how quickly an object's velocity changes over time.
Understanding Rate of Change of Velocity
Velocity is a vector quantity, meaning it has both magnitude (speed) and direction. A change in velocity can occur if the speed changes, the direction changes, or both.
The term "rate of change" always implies a division by time. So, the rate of change of velocity is calculated as:
Rate of Change of Velocity = Change in Velocity / Change in Time
According to the provided reference, the SI unit of change of velocity is m/s. Time is measured in seconds (s) in the SI system.
Therefore, the unit of the rate of change of velocity is:
(m/s) / s = m/s²
This unit, m/s², represents how many meters per second the velocity changes every second.
SI Units in Motion
Here's a quick look at the SI units for related concepts:
| Quantity | Definition | SI Unit |
|---|---|---|
| Velocity | Rate of change of position | meters per second (m/s) |
| Change in Velocity | Final velocity minus initial velocity | meters per second (m/s) |
| Rate of Change of Velocity (Acceleration) | Rate of change of velocity over time | meters per second squared (m/s²) |
It's important to note the distinction: the reference correctly states that the SI unit for a change in velocity is meters per second (m/s), just like velocity itself. However, the unit for the rate at which that change happens over time is meters per second squared (m/s²).
Practical Example
Imagine a car starting from rest and speeding up in a straight line.
- Its initial velocity is 0 m/s.
- After 5 seconds, its velocity is 10 m/s.
- The change in velocity is 10 m/s - 0 m/s = 10 m/s. (Unit: m/s)
- The rate of change of velocity (acceleration) is (10 m/s) / (5 s) = 2 m/s². (Unit: m/s²)
This means the car's velocity increased by 2 meters per second every second during that time interval.
Understanding this unit is crucial for analyzing motion and applying Newton's laws, where acceleration plays a key role (e.g., Force = mass × acceleration).
