Building a space station, in which astronauts would live for a considerable time, is essential even if the space station project were to contribute no new knowledge about space or Earth that could not otherwise be obtained. For future missions to explore Mars, we will need the medical knowledge that the space station project will give us about the limits of human capacities to live in spacecraft for an extended time. The argument makes the assumption that
(A) the exploration of Mars will be carried out by people traveling in spacecraft and not by robots alone
(B) the capacities of astronauts are typical of those of ordinary human beings
(C) no unforeseen medical problems will arise on the first mission to explore Mars
(D) a mission to Mars will be the first of many missions that will explore the solar system
(E) living in spaceship for an extended time presents insurmountable medical problems

Acommon procedure for measuring the velocity of an airstream involves the insertion of an electrically heated wire (called a hot-wire anemometer) into the airflow, with the axis of the wire oriented perpendicular to the flow direction. the electrical energy dissipated in the wire is assumed to be transferred to the air by forced convection. hence, for a prescribed electrical power, the temperature of the wire depends on the convection coefficient, which, in turn, depends on the velocity of the air. consider a wire of length l = 20 mm and diameter d = 0.5 mm, for which a calibration of the form v = 6.25 ă— 10â’5 h2 has been determined. the velocity v and the convection coefficient h have units of m/s and w/m2 â‹… k, respectively. in an application involving air at a temperature of tâž = 25â°c, the surface temperature of the anemometer is maintained at ts = 75â°c with a voltage drop of 5 v and an electric current of 0.1 a. what is the velocity of the air?