| Glossary | ||||||||||||||
| velocity
— vector quantity that describes the rate at which position changes. Like speed, velocity has units of length over time, such as m/s. virtual image — image formed by light rays that do not converge at the location of the image. Virtual images cannot be projected or displayed on a screen. viscosity — resistance of a fluid to flow or shear deformation. For example, honey has a high viscosity and water has a low viscosity. voice coil — cylindrical coil of wire attached to the loudspeaker cone and moves in and out in response to a varying electrical signal passing through the wire. In a microphone, the equivalent device called an induction coil moves in response to sound waves, inducing a varying electrical signal in the wire. volt (V) — unit of electric potential and electric potential difference. voltage — amount of electrical potential energy that each unit of electric charge has. Also called potential difference. Measured in volts (V). voltmeter — instrument to measure the voltage, or potential difference, across one or more components of a closed circuit. A multimeter usually includes a voltmeter as one of its instrument settings. volume — number of cubic units that completely fill the interior space of an object. watt (W) — SI unit of power. One watt corresponds to one joule per second. wave — oscillation that travels. Waves are a traveling form of energy. They have properties of frequency, wavelength, speed, and amplitude. wave function — quantum mechanical description of a particle’s probability amplitude as a function of time and space, denoted by Ψ. wavefront — two- or three-dimensional shape of the crest of a wave. A spatial curve or surface that is the locus of all points on a given cycle of a wave that have the same phase. wavelength — spatial extent (length) of one cycle of a wave. | weak nuclear force
— one of the four fundamental forces of nature that governs the process of radioactive decay. wedge — piece of material, thick at one end and tapered at the other end, typically inserted into a crevice in order to split an object. One of six types of simple machines. weight — downward-acting force created by gravity acting on the mass of an object. Equal to mg, where g is the local strength of gravity, such as 9.8 N/kg at the Earth’s surface. Weight has the units of force, such as newtons (N) or pounds. wheel and axle — lifting machine comprised of a rope attached to a wheel such that applying a torque to the wheel winds the rope onto the axle. One of six types of simple machines. work — form of energy equal to one newton of force exerted for one meter in the direction of the force. Measured in joules (J). work function — energy needed to liberate an electron from a metal atom in the photoelectric effect. work–energy theorem — change in the kinetic energy of an object equals the net work done on it. x-rays — high frequency form of electromagnetic radiation. zeroth law of thermodynamics — if two systems are in thermal equilibrium with a third system, then they are also in thermal equilibrium with each other. The implication of the zeroth law is that no heat will flow between two objects at the same temperature. | |||||||||||||
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