Midterm Numbers To Know

Question 1

watts per human power

Answer 1

100

Question 2

melting/freezing temperature of water

Answer 2

273.15 k

Question 3

boiling point of pure water at Earth’s atmospheric pressure

Answer 3

393.15 k

Question 4

the approximate mechanical efficiency of most engines

Answer 4

20%

Question 5

the approximate electrical efficiency of most electrical motors and electrical generators

Answer 5

90%

Question 6

the age of the universe

Answer 6

13.7 billion years

Question 7

average depth of the Earth’s ocean

Answer 7

4 km

Question 8

the fraction of the surface of the Earth covered by ocean

Answer 8

70%

Question 9

the approximate thickness of the Earth’s atmosphere

Answer 9

80 km

Question 10

the age of the Earth

Answer 10

4.6 billion years

Question 11

the first evidence of life on Earth

Answer 11

3-4 billion years ago

Question 12

the first evidence of multi-celled organisms

Answer 12

1 billion years ago

Question 13

life first colonizes land

Answer 13

400 million years ago

Question 14

first mammals appeared

Answer 14

225 million years ago

Question 15

extinction of the dinosaurs (except for birds, which survived)

Answer 15

65 million years ago

Question 16

first hominids appeared

Answer 16

5 million years ago

Question 17

first modern humans appeared

Answer 17

200,000 years ago

Question 18

date of the first human civilization

Answer 18

8000 BC

Question 19

start of the industrial revolution

Answer 19

1760

Question 20

global human population at the start of the industrial revolution

Answer 20

1 billion people

Question 21

current human population

Answer 21

8 billion people

Question 22

current rate of human population growth

Answer 22

1%

Question 23

population of the U.S.

Answer 23

300 million people

Question 24

total per capita power utilization in the U.S.

Answer 24

12 kW

Question 25

total per capita power utilization in the world

Answer 25

2 kW

Question 26

the fraction of total energy used for industrial, transportation, commercial, and residential purposes

Answer 26

25%

Question 27

the fraction of total energy derived from fossil fuel sources

Answer 27

85%

Question 28

the approximate current EPR for fossil fuels

Answer 28

5-10

Question 29

the approximate date that domestic oil utilization peaked in the U.S.

Answer 29

1975

Question 30

the residence time of CO2 in the Earth’s atmosphere (life span in the atmosphere)

Answer 30

100 years

Question 31

the flux of solar energy at 1 AU

Answer 31

1370 Wm^-2

Question 32

the maximum solar flux at the Earth’s surface

Answer 32

1000 Wm^-2

Question 33

the infrared emissivity of most non-metals

Answer 33

1

Question 34

the infrared emissivity of most metals

Answer 34

0.05

Question 35

the specific heat of most materials

Answer 35

1000 J kg^-1 k^-1

Question 36

the specific heat of liquid water

Answer 36

4186 J kg^-1 k^-1

Question 37

the thermal conductivity of most non-insulating materials

Answer 37

1 W m^-1 k^-1

Question 38

the daily average solar flux for the Earth (including day/night and latitude)

Answer 38

342 W m^-2

Question 39

the maximum efficiency of silicon solar cells

Answer 39

0.25

Question 40

the maximum efficiency of silicon solar panels

Answer 40

0.2

Question 41

the average near-surface geothermal gradient (increase in temperature with depth in the Earth)

Answer 41

25 k/km

Question 42

the average rate of Earth’s plate motions

Answer 42

2 cm/year