The peak luminosity of a white dwarf supernova is around 1010 Lsun, and it remains brighter than 108 Lsun for about 150 days. In comparison, the luminosity of a bright Cepheid variable star is about 10,000 Lsun. The Hubble Space Telescope is sensitive enough to make accurate measurements of apparent brightness for Cepheid variable stars up to a distance of about 100 million light-years. Estimate the distance of a fading white dwarf supernova of luminosity 108 Lsun whose apparent brightness is comparable to that of a bright Cepheid variable star 100 million light-years from Earth. How does the distance of that supernova compare to the size of the observable universe?

Astudent is given an assignment to demonstrate diffraction. he takes a photograph of a straw in a glass of water. the straw appears bent at the water level. which best describes this example? a) this is a good example of diffraction. b) this is an example of dispersion and not diffraction. c) this is an example of refraction and not diffraction. d) this is an example of reflection and not diffraction.

Total solidification times of three casting geometries are to be compared: a sphere, a cylinder, in which the length-to-diameter ration - 1.0, and a cube. volume = 1000 cm^3 for all three shhapes, and the same casting alloy is used. a) determine the solidification times of each geometry b) based on the results of part (a), which geometric element would make the best riser? c) if the mold constant = 3.5 min/cm^2 in chvorinov's rule, compute the total solidification time for each casting.

The chart shows the costs and shipping times for materials that a company needs to build a new product. which describes the best trade-off if the company needs to start building their product within the next two years? they should order the domestic materials because it is always best to choose the fastest shipping time. they should order the imported materials because it is always best to choose the lowest cost for materials. since the shipping time is longer, they should order the domestic materials because the additional cost is worth it to get the materials in time. even though the shipping time is longer, they should order the imported materials because they are less expensive and should arrive in plenty of time to build the product.