Inertial reference frame

Definition

An inertial reference frame is a frame of reference in which an object remains at rest or moves at a constant velocity unless acted upon by an external force. It is crucial for the formulation of Newton's laws of motion.

5 Must Know Facts For Your Next Test

1. Inertial reference frames are non-accelerating frames where Newton's first law holds true.
2. Any two inertial reference frames move relative to each other at constant velocity.
3. Observers in different inertial frames will measure the same laws of physics.
4. The concept is vital for distinguishing between real forces and fictitious forces.
5. Earth is approximately an inertial reference frame for most everyday purposes, but not perfectly due to rotation and gravitational influences.

Review Questions

• What conditions must be met for a reference frame to be considered inertial?
• How do observers in different inertial reference frames perceive the laws of physics?
• Why is Earth often approximated as an inertial reference frame?

Related terms

Newton's First Law:

An object will remain at rest or move in a straight line with constant speed unless acted upon by a net external force.

Non-Inertial Reference Frame:

A frame of reference that is accelerating, where fictitious forces like centrifugal force appear.

Fictitious Force: A force that appears to act on a mass when observed from a non-inertial reference frame, such as centrifugal force or Coriolis force.