Within which type of system is the total energy conserved? A. Isolated
B. Connected
C. Closed
D. Open

An observer that stands still as the electron moves by him, will observe

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.

How do we measure or think of speed in the united states?