phase angle

physics

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major reference

In phase
…period, having passed through a phase angle of 90°, or π/2 radians. In this example the motion of the minute hand is a uniform circular motion, but the concept of phase also applies to simple harmonic motion such as that experienced by waves and vibrating bodies.
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alternating current

In electricity: Behaviour of an AC circuit
The phase angle ϕ in equation (29) gives the time relationship between the current in the circuit and the driving electromotive force, V₀ cos(ωt). The tangent of the angle ϕ is
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inertia

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inertia

physics

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Related Topics:: moment of inertia; motion; Mach’s principle; equivalence principle; rotational inertia

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inertia, property of a body by virtue of which it opposes any agency that attempts to put it in motion or, if it is moving, to change the magnitude or direction of its velocity. Inertia is a passive property and does not enable a body to do anything except oppose such active agents as forces and torques. A moving body keeps moving not because of its inertia but only because of the absence of a force to slow it down, change its course, or speed it up.

There are two numerical measures of the inertia of a body: its mass, which governs its resistance to the action of a force, and its moment of inertia about a specified axis, which measures its resistance to the action of a torque about the same axis. See Newton’s laws of motion.

Keep Learning

How does inertia affect our everyday lives?
How do Newton's laws of motion relate to inertia?
Why do seat belts save lives during car accidents?
How does inertia work in space where there is no gravity?

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Adam Augustyn.