Several middle school students want to build 30 solar eclipse projectors for children at an elementary school to use. The projectors make it easy and safe for people to view a solar eclipse. One possible design of a student-constructed solar eclipse projector is shown below. Image courtesy of NASA

Which of the following would be the most reasonable criterion the students should consider before building the projectors?
A.
It should be small enough to fit in a school backpack.
B.
It should be made of heavy enough materials so that it cannot easily be moved.
C.
It should be durable enough so that if it is dropped, it will not break.
D.
It should be made mostly of metal materials.

Agas mixture consists of 8 kmol of h2 and 2 kmol of n2. determine the mass of each gas and the apparent gas constant of the mixture.

Water vapor initially at 10 bar and 400 °c is contained within a piston-cylinder assembly. the water lost heat to the surrounding according to isochoric (iso-volumetric) process until its temperature is 150 °c. the water is then condensed isothermally to saturated liquid. for the water as a system, calculate the work in kj/kg

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c