In our widget example, we will assume that the fixed cost for the stapler, pen, and âfactoryâ is $10 and the cost of each worker hired is $5 per worker. Since fixed costs are constant, the firm incurs $10 regardless of the level of output. Labor is the only variable cost computed by $5 times the number of workers.
How Bull Sharks Can Live in Both Ocean and Fresh Water. Although there are a handful of species that live in freshwater, we tend to think of sharks as being ocean dwellers. But there is also a very unique shark that can live in both ocean and fresh water estuaries and lakes: the Bull Shark.
Sharks typically swim with the even, liquid grace of a creature completely at home with its place in the Universe. Large sharks generally cruise at a leisurely 1.5 miles (2.4 kilometres) per hour. Because most species fare poorly in captivity, the maximum swimming speed of a shark has seldom been measured. The Blue Shark (Prionace glauca) is an open ocean glider, planing on wing-like pectoral fins and flattened belly.