adam_vink t1_jb10yht wrote on March 5, 2023 at 4:51 PM

Reply to comment by KWOOOSH in How is it that objects in equilibrium stay in motion at constant velocity? by KWOOOSH

Yes, that is just inertia by definition (see below definition from dictionary.com) "the property of matter by which it retains its state of rest or its velocity along a straight line so long as it is not acted upon by an external force."

adam_vink t1_jb100zc wrote on March 5, 2023 at 4:44 PM

Reply to How is it that objects in equilibrium stay in motion at constant velocity? by KWOOOSH

You're confused because you think "at rest" and "in motion" are different things, but they're not. They're the same.

Imagine two space ships, Firefly and Enterprise, in deep space set on a collision course. The captain of the Enterprise radios the captain of the Firefly saying, "Firefly, you're moving towards us at 1000m/s. Please engage reverse thrusters to match our velocity or alter your course." The captain of the Firefly responds, "No, Enterprise. YOU'RE moving towards US at 1000m/s. You engage YOUR reverse thrusters or alter YOUR course."

Who is right? Both, and neither. Both are correct from their own inertial reference frame, and both are incorrect from the other's inertial reference frame.