A home uses about 4*10^11 power joules of energy each year. In many parts of the United States there are about 3000 h of sunlight each year. How much energy from the sun falls on one square meter each year? If the solar energy can be converted to useful energy with an efficiency of 20%, how large an area of converters would produce the energy needed by the home?

The Sun transfers in each second and amount of 1367J per square meter, so in hour it can transfer:

E = 60*60*1367 J/h*m2 = 4,921,200 J/h*m^2.

in one year, we have 3000h*4,921,200 J/h*m^2. = 14,763,600,000 Joules per square meter.

Now, only 20% of this can be used as energy, so the amount that can be used is:

E = 0.2* 14,763,600,000 J/m^2 = 2,952,720,000 J/m^2

Now, we want to find the number X of square meters such:

X*2,952,720,000 J/m^2 = 4x10^11 J

X = ( 4x10^11 J)/(2,952,720,000 J/m^2) = 135.5 m^2

So you only need around 135.5 square metters per house.

relativism, roughly put, is the view that truth and falsity, right and wrong, standards of reasoning, and procedures of justification are products of differing conventions and frameworks of assessment and that their authority is confined to the context giving rise to them. more precisely, “relativism” covers views which maintain that—at a high level of abstraction—at least some class of things have the properties they have (e.g., beautiful, morally good, epistemically justified) not simpliciter, but only relative to a given framework of assessment (e.g., local cultural norms, individual standards), and correspondingly, that the truth of claims attributing these properties holds only once the relevant framework of assessment is specified or supplied. relativists characteristically insist, furthermore, that if something is only relatively so, then there can be no framework-independent vantage point from which the matter of whether the thing in question is so can be established.

relativism has been, in its various guises, both one of the most popular and most reviled philosophical doctrines of our time. defenders see it as a harbinger of tolerance and the only ethical and epistemic stance worthy of the open-minded and tolerant. detractors dismiss it for its alleged incoherence and uncritical intellectual permissiveness. debates about relativism permeate the whole spectrum of philosophical sub-disciplines. from ethics to epistemology, science to religion, political theory to ontology, theories of meaning and even logic, philosophy has felt the need to respond to this heady and seemingly subversive idea. discussions of relativism often also invoke considerations relevant to the very nature and methodology of philosophy and to the division between the so-called “analytic and continental” camps in philosophy. and yet, despite a long history of debate going back to plato and an increasingly large body of writing, it is still difficult to come to an agreed definition of what, at its core, relativism is, and what philosophical import it has. this entry attempts to provide a broad account of the many ways in which “relativism” has been defined, explained, defended and criticized.

explanation:

heats surface water up