Background: A phonograph record (also known as a gramophone record, especially in British English, or record) is an analog sound storage medium in the form of a flat disc with an inscribed, modulated spiral groove. The groove usually starts near the periphery and ends near the center of the disc. At first, the discs were commonly made from shellac; starting in the 1950s polyvinyl chloride became common. In recent decades, records have sometimes been called vinyl records, or simply vinyl, although this would exclude most records made until after World War II.
Context: The playing time of a phonograph record depends on the available groove length divided by the turntable speed. Total groove length in turn depends on how closely the grooves are spaced, in addition to the record diameter. At the beginning of the 20th century, the early discs played for two minutes, the same as cylinder records. The 12-inch disc, introduced by Victor in 1903, increased the playing time to three and a half minutes. Because the standard 10-inch 78 rpm record could hold about three minutes of sound per side, most popular recordings were limited to that duration. For example, when King Oliver's Creole Jazz Band, including Louis Armstrong on his first recordings, recorded 13 sides at Gennett Records in Richmond, Indiana, in 1923, one side was 2:09 and four sides were 2:52-2:59.  In January 1938, Milt Gabler started recording for Commodore Records, and to allow for longer continuous performances, he recorded some 12-inch discs. Eddie Condon explained: "Gabler realized that a jam session needs room for development." The first two 12-inch recordings did not take advantage of their capability: "Carnegie Drag" was 3m 15s; "Carnegie Jump", 2m 41s. But at the second session, on April 30, the two 12-inch recordings were longer: "Embraceable You" was 4m 05s; "Serenade to a Shylock", 4m 32s. Another way to overcome the time limitation was to issue a selection extending to both sides of a single record. Vaudeville stars Gallagher and Shean recorded "Mr. Gallagher and Mr. Shean", written by Irving and Jack Kaufman, as two sides of a 10-inch 78 in 1922 for Cameo. Longer musical pieces were released as a set of records. In 1903 HMV in England made the first complete recording of an opera, Verdi's Ernani, on 40 single-sided discs. In 1940, Commodore released Eddie Condon and his Band's recording of "A Good Man Is Hard to Find" in four parts, issued on both sides of two 12-inch 78s. The limited duration of recordings persisted from their advent until the introduction of the LP record in 1948. In popular music, the time limit of  3 1/2 minutes on a 10-inch 78 rpm record meant that singers seldom recorded long pieces. One exception is Frank Sinatra's recording of Rodgers and Hammerstein's "Soliloquy", from Carousel, made on May 28, 1946. Because it ran 7m 57s, longer than both sides of a standard 78 rpm 10-inch record, it was released on Columbia's Masterwork label (the classical division) as two sides of a 12-inch record. The same was true of John Raitt's performance of the song on the original cast album of Carousel, which had been issued on a 78-rpm album set by American Decca in 1945.  In the 78 era, classical-music and spoken-word items generally were released on the longer 12-inch 78s, about 4-5 minutes per side. For example, on June 10, 1924, four months after the February 12 premier of Rhapsody in Blue, George Gershwin recorded an abridged version of the seventeen-minute work with Paul Whiteman and His Orchestra. It was released on two sides of Victor 55225 and ran for 8m 59s.
Question: What is a 78 rpm recording time?. Whats the answer?
The playing time of a phonograph record depends on the available groove length divided by the turntable speed.