Animations demonstrating the equivalence principle:

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Accelerating Elevator

An observer in an accelerating elevator in the absence of a gravitational field (left side) observes the same physical laws as an observer in a stationary elevator in the presence of a gravitational field (right side)

Accelerating Elevator - 2

An observer in an accelerating elevator in the absence of a gravitational field (left side) observes the same physical laws as an observer in a stationary elevator in the presence of a gravitational field (right side). The gray line (left side) follows the path of the ball viewed from an inertial frame.

Elevator in Freefall

An observer in an elevator in freefall in the presence of a gravitational field (left side) observes the same physical laws as an observer in an inertial frame in the absence of a gravitational field (right side). The gray line follows the path of the ball in the Earth frame (left) and the elevator frame (right).