Pourquoi doit-on toujours préciser le référentiel dans lequel est étudié le mouvement d'un système?

For this car, predict the shape of a graph that shows distance (x) versus time (t). note that time is the independent variable and will be on the bottom axis. need asap

A2.0 μf capacitor and a 4.0 μf capacitor are connected in series across a 0.827-kv potential. the charged capacitors are then disconnected from the source and connected to each other with terminals of like sign together. find the voltage across each capacitor.

The energy released by a nuclear fusion reaction is produced when