Atrain is speeding down a railroad track at a speed of 50 miles per hour. from whose reference point is the train not moving?

Passengers on the train, and flies on the passengers, can be sleeping or reading books. In their reference frames, the train is not moving.

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

d eras and periods