Tag: science & technology

The X-15 rocket-powered aircraft holds the official record for the fastest manned aircraft at Mach 6.72 (4,520 mph), set by William J. Knight on October 3, 1967. While the SR-71 Blackbird is often cited as the fastest air-breathing aircraft at Mach 3.3+, the X-15 was rocket-powered and reached much higher speeds in the upper atmosphere.

The X-15 rocket-powered aircraft holds the official record for the fastest manned aircraft at Mach 6.72 (4,520 mph), set by William J. Knight on October 3, 1967. While the SR-71 Blackbird is often cited as the fastest air-breathing aircraft at Mach 3.3+, the X-15 was rocket-powered and reached much higher speeds in the upper atmosphere. This is a duplicate of question 48622.

The F-22 Raptor was indeed the first production fighter aircraft with sustained supersonic cruise capability (supercruise) without using afterburners. It entered service in 2005. While the Concorde had supersonic cruise, it was a passenger aircraft not a fighter. Other options like F-16, F-18, and Su-30 require afterburners for supersonic flight.

The Robinson R-22 is a two-bladed, single-engine light helicopter manufactured by Robinson Helicopter Company since 1979. With over 7,000 units produced, it is the world's best-selling civilian helicopter, widely used for training and personal transportation. The Bell 206 JetRanger is also popular but has lower production numbers, while the Mi-17 is a military transport helicopter, and the AH-64 Apache is an attack helicopter.

The HAL Cheetal helicopter has the highest service ceiling among the options listed, capable of operating at very high altitudes. Service ceiling refers to the maximum altitude at which an aircraft can maintain steady level flight. The other helicopters listed have lower operational ceilings.

p.r.n. is the medical abbreviation for 'pro re nata' - Latin for 'when necessary' or 'as the occasion arises'. It indicates that a medication should be taken only when needed, not on a fixed schedule. Options B and C ('As necessary' and 'if necessary') are essentially the same meaning as A but A is the standard medical terminology.

p.o. is the medical abbreviation for 'per os' - Latin for 'by mouth' or orally. This indicates medication should be swallowed or taken by the oral route. 'by rectal' would be p.r., 'by subcutaneous' would be s.c. or s.q., and 'topical' would be applied externally to the skin.

ut dict. is the medical abbreviation for 'ut dictum' - Latin for 'as directed' or 'as has been said'. It indicates that a medication should be taken exactly as instructed by the physician. This is standard medical terminology for physician-discretionary dosing instructions.

p.c. is the medical abbreviation for 'post cibum' - Latin for 'after meals' (literally 'after food'). This timing instruction is important because food can affect medication absorption. The other options are incorrect: 'before meals' is a.c. (ante cibum), 'during meals' is rarely used as a standard abbreviation, and 'before sleep' is h.s. (hora somni).