Please give me the correct answer as I have asked these before and you guys keep
ID: 1318850 • Letter: P
Question
Please give me the correct answer as I have asked these before and you guys keep giving me wrong answers. Thank you
1---Which of the following statements is true (only one):
a.
Renewable energy resources now make up more than half of US energy consumption.
b.
Oil use has expanded more than any other fuel since 1940.
c.
We reached the point last year where we imported no oil.
d.
Electricity use has actually fallen since 1975.
2---If the growth rate of the number of solar collectors is 7% per year, what is the time for the number of solar collectors to double?
3---If the growth rate of the number of solar collectors is 7% per year, then 1000 units in use in 2010 will grow to _______ units by the year 2040.
4---The
a.
Renewable energy resources now make up more than half of US energy consumption.
b.
Oil use has expanded more than any other fuel since 1940.
c.
We reached the point last year where we imported no oil.
d.
Electricity use has actually fallen since 1975.
Explanation / Answer
1.d.Electricity use has actually fallen since 1975.
2.rule of 72 72/7 is roughly 10 years
3.30 years of 7%growth
1000(1+0.07)^30 = 1000* 76.1 =7610 or about 8000 units
4.The efficiency for anything...anything...even you...is simply useful output divided by all the input. In shorthand, that's e = O/I. And there's your ratio, O/I...output over input.
How's the output of that light-bulb on your desk measured? Probably Watts, like a 60 W light bulb. That's O. What's I in input to that bulb? That would be VI the volts times the current drawn. For example, if V = 120 v and I = 1 amp, then the input is VI = 120 Watts so the efficiency is e = 60/120 = 50%. [Note: I used DC for simplicity.]
5) . 20 / (.30 * .40) = 200 / 120 = 16%