Problem: The great Navicella mosaic (13051313) in the atrium of the Old St. Peter's is attributed to Giotto di Bondone. The giant mosaic, commissioned by Cardinal Jacopo Stefaneschi, was originally situated on the eastern porch of the old basilica and occupied the whole wall above the entrance arcade facing the courtyard. It depicted St. Peter walking on the waters. This extraordinary work was mainly destroyed during the construction of the new St. Peter's in the 17th century. Navicella means "little ship" referring to the large boat which dominated the scene, and whose sail, filled by the storm, loomed over the horizon. Such a natural representation of a seascape was known only from ancient works of art.
Who did the navicella mosaic depict walking on water?
The answer is the following: St. Peter

Problem: Because the states were preexisting political entities, the U.S. Constitution did not need to define or explain federalism in any one section but it often mentions the rights and responsibilities of state governments and state officials in relation to the federal government. The federal government has certain express powers (also called enumerated powers) which are powers spelled out in the Constitution, including the right to levy taxes, declare war, and regulate interstate and foreign commerce. In addition, the Necessary and Proper Clause gives the federal government the implied power to pass any law "necessary and proper" for the execution of its express powers. Other powersthe reserved powersare reserved to the people or the states. The power delegated to the federal government was significantly expanded by the Supreme Court decision in McCulloch v. Maryland (1819), amendments to the Constitution following the Civil War, and by some later amendmentsas well as the overall claim of the Civil War, that the states were legally subject to the final dictates of the federal government.
What is another word for express powers?
The answer is the following: enumerated powers

Problem: After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus the Prussian Moritz von Jacobi created the first real rotating electric motor in May 1834 that actually developed a remarkable mechanical output power. His motor set a world record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river. It was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance.
How long did it take for Jacobi's first world record to be broken?
The answer is the following: four years

Problem: Birds fly at varying altitudes during migration. An expedition to Mt. Everest found skeletons of northern pintail Anas acuta and black-tailed godwit Limosa limosa at 5,000 m (16,000 ft) on the Khumbu Glacier. Bar-headed geese Anser indicus have been recorded by GPS flying at up to 6,540 metres (21,460 ft) while crossing the Himalayas, at the same time engaging in the highest rates of climb to altitude for any bird. Anecdotal reports of them flying much higher have yet to be corroborated with any direct evidence. Seabirds fly low over water but gain altitude when crossing land, and the reverse pattern is seen in landbirds. However most bird migration is in the range of 150 to 600 m (490 to 1,970 ft). Bird strike aviation records from the United States show most collisions occur below 600 m (2,000 ft) and almost none above 1,800 m (5,900 ft).
Where do most in air collisions occur?
The answer is the following:
below 600 m