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The following table lists the electrical power in gigawatts—the rate at which energy is consumed—used in a certain city for different hours of the day, in a typical 24-hour period, with hour 1 corresponding to midnight to 1 a.m.

Hour Power Hour Power
1 28 13 48
2 25 14 49
3 24 15 49
4 23 16 50
5 24 17 50
6 27 18 50
7 29 19 46
8 32 20 43
9 34 21 42
10 39 22 40
11 42 23 37
12 46 24 34

Find the total amount of power in gigawatt-hours (gW-h) consumed by the city in a typical 24-hour period.

The total daily power consumption is estimated as the sum of the hourly power rates, or 911 gW-h.

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The average residential electrical power use (in hundreds of watts) per hour is given in the following table.

Hour Power Hour Power
1 8 13 12
2 6 14 13
3 5 15 14
4 4 16 15
5 5 17 17
6 6 18 19
7 7 19 18
8 8 20 17
9 9 21 16
10 10 22 16
11 10 23 13
12 11 24 11
  1. Compute the average total energy used in a day in kilowatt-hours (kWh).
  2. If a ton of coal generates 1842 kWh, how long does it take for an average residence to burn a ton of coal?
  3. Explain why the data might fit a plot of the form p ( t ) = 11.5 7.5 sin ( π t 12 ) .
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The data in the following table are used to estimate the average power output produced by Peter Sagan for each of the last 18 sec of Stage 1 of the 2012 Tour de France .

Source : sportsexercisengineering.com
Average power output
Second Watts Second Watts
1 600 10 1200
2 500 11 1170
3 575 12 1125
4 1050 13 1100
5 925 14 1075
6 950 15 1000
7 1050 16 950
8 950 17 900
9 1100 18 780

Estimate the net energy used in kilojoules (kJ), noting that 1W = 1 J/s, and the average power output by Sagan during this time interval.

17 kJ

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The data in the following table are used to estimate the average power output produced by Peter Sagan for each 15-min interval of Stage 1 of the 2012 Tour de France.

Source : sportsexercisengineering.com
Average power output
Minutes Watts Minutes Watts
15 200 165 170
30 180 180 220
45 190 195 140
60 230 210 225
75 240 225 170
90 210 240 210
105 210 255 200
120 220 270 220
135 210 285 250
150 150 300 400

Estimate the net energy used in kilojoules, noting that 1W = 1 J/s.

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The distribution of incomes as of 2012 in the United States in $5000 increments is given in the following table. The k th row denotes the percentage of households with incomes between $5000 x k and 5000 x k + 4999 . The row k = 40 contains all households with income between $200,000 and $250,000 and k = 41 accounts for all households with income exceeding $250,000.

Source : http://www.census.gov/prod/2013pubs/p60-245.pdf
Income distributions
0 3.5 21 1.5
1 4.1 22 1.4
2 5.9 23 1.3
3 5.7 24 1.3
4 5.9 25 1.1
5 5.4 26 1.0
6 5.5 27 0.75
7 5.1 28 0.8
8 4.8 29 1.0
9 4.1 30 0.6
10 4.3 31 0.6
11 3.5 32 0.5
12 3.7 33 0.5
13 3.2 34 0.4
14 3.0 35 0.3
15 2.8 36 0.3
16 2.5 37 0.3
17 2.2 38 0.2
18 2.2 39 1.8
19 1.8 40 2.3
20 2.1 41
  1. Estimate the percentage of U.S. households in 2012 with incomes less than $55,000.
  2. What percentage of households had incomes exceeding $85,000?
  3. Plot the data and try to fit its shape to that of a graph of the form a ( x + c ) e b ( x + e ) for suitable a , b , c .

a. 54.3%; b. 27.00%; c. The curve in the following plot is 2.35 ( t + 3 ) e −0.15 ( t + 3 ) .
A graph of the data and a function approximating the data. The function is a very close approximation.

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Newton’s law of gravity states that the gravitational force exerted by an object of mass M and one of mass m with centers that are separated by a distance r is F = G m M r 2 , with G an empirical constant G = 6.67 x 10 −11 m 3 / ( k g · s 2 ) . The work done by a variable force over an interval [ a , b ] is defined as W = a b F ( x ) d x . If Earth has mass 5.97219 × 10 24 and radius 6371 km, compute the amount of work to elevate a polar weather satellite of mass 1400 kg to its orbiting altitude of 850 km above Earth.

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Practice Key Terms 1

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Source:  OpenStax, Calculus volume 1. OpenStax CNX. Feb 05, 2016 Download for free at http://cnx.org/content/col11964/1.2
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