Problem: Cordwood construction can save significant space and was often used with wire-ended components in applications where space was at a premium (such as missile guidance and telemetry systems) and in high-speed computers, where short traces were important. In cordwood construction, axial-leaded components were mounted between two parallel planes. The components were either soldered together with jumper wire, or they were connected to other components by thin nickel ribbon welded at right angles onto the component leads. To avoid shorting together different interconnection layers, thin insulating cards were placed between them. Perforations or holes in the cards allowed component leads to project through to the next interconnection layer. One disadvantage of this system was that special nickel-leaded components had to be used to allow the interconnecting welds to be made. Differential thermal expansion of the component could put pressure on the leads of the components and the PCB traces and cause physical damage (as was seen in several modules on the Apollo program). Additionally, components located in the interior are difficult to replace. Some versions of cordwood construction used soldered single-sided PCBs as the interconnection method (as pictured), allowing the use of normal-leaded components.
What force caused the physical damage to components that affected the Apollo program?
The answer is the following: Differential thermal expansion

Problem: There were four major HDTV systems tested by SMPTE in the late 1970s, and in 1979 an SMPTE study group released A Study of High Definition Television Systems:
Who tested the four major HDTV systems in the late 1970's?
The answer is the following: SMPTE

Problem: Greece attracts more than 16 million tourists each year, thus contributing 18.2% to the nation's GDP in 2008 according to an OECD report. The same survey showed that the average tourist expenditure while in Greece was $1,073, ranking Greece 10th in the world. The number of jobs directly or indirectly related to the tourism sector were 840,000 in 2008 and represented 19% of the country's total labor force. In 2009, Greece welcomed over 19.3 million tourists, a major increase from the 17.7 million tourists the country welcomed in 2008.
What did the 2008 OECD report show the average tourist expenditure while in Greece was?
The answer is the following: $1,073

Problem: According to conservation of energy, energy can neither be created (produced) nor destroyed by itself. It can only be transformed. The total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. Energy is subject to a strict global conservation law; that is, whenever one measures (or calculates) the total energy of a system of particles whose interactions do not depend explicitly on time, it is found that the total energy of the system always remains constant.
According to what, energy can neither be created nor destroyed by itself?
The answer is the following:
conservation of energy