No, acceleration is generally not zero in a non-inertial frame of reference. In fact, a non-inertial frame is defined by its acceleration relative to an inertial frame.
A common understanding in physics defines frames of reference based on whether they are accelerating:
Understanding Reference Frames
To provide a precise answer, it's essential to differentiate between two fundamental types of reference frames:
- Inertial Frame of Reference: This is a frame where Newton's First Law of Motion (the law of inertia) holds true. An object at rest remains at rest, and an object in motion continues in motion with constant velocity, unless acted upon by a net external force. Crucially, an inertial frame is either at rest or moving at a constant velocity relative to distant stars. Therefore, the acceleration of an inertial frame itself is zero.
- Non-Inertial Frame of Reference: This is a frame that is accelerating (either linearly or rotationally) relative to an inertial frame. Because it is accelerating, observers within a non-inertial frame will observe objects behaving in ways that appear to violate Newton's First Law, unless "fictitious forces" (or inertial forces) are introduced to account for the frame's acceleration.
Addressing the Provided Reference
It is important to note that the provided reference states: "The reference frame which has zero acceleration is called a non-inertial frame of reference." This statement contradicts the universally accepted definition within the field of physics. According to standard physics principles, a frame with zero acceleration is an inertial frame, while a non-inertial frame is one that is accelerating.
Why Non-Inertial Frames Have Acceleration
The acceleration of a non-inertial frame is what distinguishes it from an inertial one. This acceleration can be:
- Linear Acceleration: For example, a car rapidly accelerating forward or braking to a stop. Objects inside the car would experience an apparent force in the opposite direction of the car's acceleration.
- Rotational Acceleration: Such as a rotating carousel or the Earth's rotation. Objects on the carousel experience centrifugal and Coriolis forces, which are examples of fictitious forces arising from the frame's rotation.
These fictitious forces are necessary in non-inertial frames to make Newton's laws appear to hold. They are not real forces in the sense of being caused by an interaction with another object but are a consequence of the observer's accelerating frame of reference.
Key Characteristics Comparison
| Feature | Inertial Frame | Non-Inertial Frame |
|---|---|---|
| Acceleration (relative to absolute space) | Zero or Constant Velocity | Non-zero acceleration |
| Newton's First Law | Holds True | Requires Fictitious Forces to hold |
| Example | A car moving at steady speed | A braking car, a rotating merry-go-round |
In summary, a non-inertial frame of reference is characterized by its non-zero acceleration relative to an inertial frame, leading to the appearance of fictitious forces.
