The rate of change in the velocity of an object is called acceleration.
Understanding Acceleration
Acceleration is a fundamental concept in physics that describes how quickly an object's velocity changes over time. Velocity itself is a vector quantity, meaning it has both magnitude (speed) and direction. When either the speed or the direction of an object's motion changes, the object is accelerating.
As stated in the reference: Acceleration is the rate at which an object changes its velocity. It is a vector quantity like velocity. Its unit is m/s². (Correction: The reference says "m/s", which is the unit for velocity. The standard unit for acceleration is m/s²).
Key Characteristics of Acceleration
- Vector Quantity: Just like velocity, acceleration has both magnitude and direction. This means the direction of acceleration is important. If an object is speeding up, the acceleration is in the same direction as the velocity. If it's slowing down (decelerating), the acceleration is in the opposite direction of the velocity.
- Rate of Change: It measures how fast the velocity is changing. A higher acceleration means the velocity is changing more rapidly.
- Unit: The standard international (SI) unit for acceleration is meters per second squared (m/s²). This unit reflects the change in velocity (m/s) per unit of time (s).
How Acceleration Works
Acceleration occurs in various situations:
- Speeding Up: A car accelerating from rest. Its velocity magnitude increases.
- Slowing Down: A car braking to a stop. Its velocity magnitude decreases (often called deceleration, but it's still a form of acceleration in the opposite direction of motion).
- Changing Direction: An object moving at a constant speed in a circle is constantly changing its direction of velocity, thus it is accelerating (specifically, undergoing centripetal acceleration).
Examples
- A car increasing its speed from 20 m/s to 30 m/s over 5 seconds is accelerating.
- A ball thrown upwards slows down as it rises due to the downward acceleration of gravity.
- An airplane turning during flight is accelerating even if its speed remains constant.
Summary Table: Velocity vs. Acceleration
| Feature | Velocity | Acceleration |
|---|---|---|
| Definition | Rate of change of displacement | Rate of change of velocity |
| Quantity Type | Vector | Vector |
| SI Unit | m/s | m/s² |
| What it Measures | How fast and in what direction an object is moving | How fast an object's velocity is changing |
