Signal Quality. Spektrum telemetry modules keep tabs on the quality of the signal coming to the receiver and send this information back to the transmitter where it is represented on the LCD screen using a familiar signal bar scale.
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position.
According to Newton's 1st Laws of Motion, an object in motion continues in the same path / direction unless acted on by an outside force. Even though the pendulum appears to change paths, it is actually the Earth rotating underneath the pendulum. Describe how Foucault's Pendulum gives evidence to the Earth's rotation on its axis.