Ch 3 Textbook/ slides

Question 1

Power eqt w/ units

Answer 1

Power (watts)= work (J)/time (s)

Power (watts)= Energy (J) /time (s)

Question 2

Power: Measure of

The amount of _ done or _ expended

The amount of _ it takes to do that _

Answer 2

Power: Measure of

The amount of work done or energy expended

The amount of time it takes to do that work

Question 3

Power and energy: Energy eqt

Answer 3

Energy (joules)= power (watts) x time (seconds)

Question 4

Describe energy changes during bungee jump

• Energy to top
• where does PE come from
• fall
• bounce

Answer 4

• Jumper transforms chemical potential energy from food to kinetic energy in the muscles
• Work done against gravity provides the jumper gravitational potential energy at the top
• During the long descent, the gravitational potential energy diminishes, while the jumper’s kinetic energy and thermal energy simultaneously increases
• As the cords begin to stretch, the jumper slows down and kinetic energy gradually is converted to stored elastic potential energy in the cords and thermal energy
• Eventually, the gravitational potential energy that the jumper had at the beginning is completely transferred to the stretched elastic cords, which then rebound, converting some of the stored elastic energy back into kinetic energy and gravitational potential energy.
• All the time, some of the energy is also converted to thermal energy: increased temperature in the stressed cord, on the jumper’s ankles, and the air as it is pushed aside.

Question 5

Name the trophic levels (5)

Answer 5

• First
  
  • All plants that produce their energy through photosynthesis
• SecondHerbivores
  
  • Eat plants from 1st level
  • Cows, insects
• Third
  
  • Carnivores
  • Eat 2nd level
  • Wolves, lions
• 4th
  
  • Carnivores that eat carnivores
  • Killer whales
• Other
  
  • Eat dead organisms form all
  • Termites, vultures, bacteria, fungi
• Span the trophic levels
  
  • Omnivores
  • Eat all levels
  • Humans, bears, venus fly trap

Question 6

Describe energy loss between trophic levels and why

Answer 6

• 10% of solar energy is available for plants to transform into chemical energy
• Less than 10% of plant chem potential energy becomes tissue in other animals
• Less than 1% of the OG energy in sunlight (10% of 10%)
• Loss in metabolic processes

Question 7

First law of thermodynamics

In an isolated/closed system, the total amount of _, including _ , is conserved

Answer 7

First law of thermodynamics

In an isolated/closed system, the total amount of energy, including heat , is conserved

Question 8

why

Whole grains cost 1/10th of meat

Answer 8

It takes 10 times as much energy to make the 1 lb of beef than 1 lb of wheat

Question 9

why dinos warm blooded

Answer 9

• More herbivore skeletons than carnivore10 to 1 ratio
• Same ratio of warm blooded herbivore animals to warm blooded carnivores today
• Cold blooded much higher so DINOSAURS were warm blooded

Question 10

why earth and sun closed system

Answer 10

No significant amount of energy or matter are being added from outside sources

Question 11

difference between kcal and cal

Answer 11

• The physical unit “calorie” is the energy required to increase the temperature of one gram of water by 1 degree Celsius
• dietary Calorie is a kcal = 1000 calories

Question 12

You consume _ calories to gain a lb of fat

Answer 12

You consume 3500 calories to gain a lb of fat

Question 13

maintain weight eqt

lose weight eqt

Answer 13

To maintain your weight

• X lbs * 15 calories/lb

Lose pounds

• 3500 calories/ x days= # calories reduce your diet by

Question 14

How did the discovery that mass is a form of energy resolve the debate over Earth’s age?

Answer 14

Kelvin calculated time earth too cool to present temperature based on rate energy radiated out into space- less than 100mil

Found out rocks have radioactive elements. Thermal energy is generated by the conversion of mass as they decay

Question 15

the growth of modern technological societies since the Industrial Revolution has been driven by the availability of _ and _ sources of energy

Answer 15

the growth of modern technological societies since the Industrial Revolution has been driven by the availability of cheap and high-grade sources of energy

Question 16

us #1 source of E

2 probs

Answer 16

1 petroleum

2 problems

• Fossil fuels are not replaceable
• Adds CO2 to the atmosphere- lead to global warming

Question 17

1 (2)

US alt energy

Answer 17

Alt energy

Biomass collectively #1

Hydropower #1 alone

Question 18

describe 3 gens of biomass

Answer 18

1st-edible

2nd- non edible

3rd-algae

Question 19

1 source-

Freshwater withdrawals

When economy goes down so does __

Answer 19

1 source- surface water

Freshwater withdrawals

When economy goes down so does __

Question 20

hydroelectric power can meet total energy demand of in western states t/f

Answer 20

true

Question 21

Use less water- thermoelectric

New power plants converted to water efficient__

Decrease use in _

Increase use of _

Closing plants with _ cooling systems

Answer 21

New power plants converted to water efficient cooling technology

Decrease use in coal

Increase use of natural gas

Closing plants with once-through cooling systems

Question 22

base load vs peak

• what supplies elect
• where alt energy

Answer 22

• base= daily
• Coal/ nuclear plants
• peak= extra
• Gas turbinesCheap to build, but expensive to operate
• More expensive fuels
• Alt energy peak-comparable cost

Question 23

t/f all US energy can be generate from wind

Answer 23

true

Question 24

problem w/ ethanol

solution?

Answer 24

• Made form corn kernels
• Competes with corn as a food for humans and animals
• Cellulosic ethanol (2nd gen)

Question 25

2 major problems w renewables

Answer 25

• intermittent
• need storage system

Question 26

__ of US energy budget is spent on transportation

Answer 26

1/3

Question 27

pros and cons of electric cars

Answer 27

Pro

• Less fossil fuel use

Con

• Water used in electric generation
• Converting chemical to electrical energy.. There is energy loss

Question 28

Prescott Joule is noted in science for his discovery that

_ (mechanical energy) could be transformed into _

Answer 28

Prescott Joule is noted in science for his discovery that

motion (mechanical energy) could be transformed into heat

Question 29

As work is performed on the planet Earth, some energy is lost in the form of

Answer 29

Heat

Question 30

The energy balance of the earth means

Answer 30

the amount of solar energy absorbed by Earth equals the amount of heat energy radiated from Earth minus the work done

Question 31

Energy can be stored in a flashlight battery as

Answer 31

chemical potential energy

Question 32

In place of the kilowatt, a metric unit, the English system uses the unit

Answer 32

kw= Horse power

Question 33

Energy can be defined as

The ability to do _

F*_

Work

Power*_

Answer 33

Energy can be defined as

The ability to do work

F*d

Work

Power (watts= J/s)*t

Question 34

The rating of a light bulb at 100 watts indicates

Answer 34

the rate of energy that the bulb consumes

Question 35

What is the difference between energy and power? What is a unit of power?

Answer 35

Energy= ability to do work

Power= rate work is done or rate energy is consumedUnit

P=W/t

Watts=Joules/seconds

Question 36

What is the relationship between heat, energy, and the motion of atoms?

Answer 36

All atoms are in constant motion (KE)

Faster moving atoms= posses more thermal energy

Question 37

Explain how sound is actually a form of energy. In what medium do sound waves travel?

Answer 37

Sound is produced by vibrating objects. When an object is hit or vibrations are produced in I, the air particles or particles of the medium around it also start vibrating. The KE of the particles is associated with the energy of the sound wave. The vibrations of the particles or their KE it what actually sound is.

Question 38

What does it mean to say that different forms of energy are interchangeable?

Answer 38

We mean that total energy content of system remains constant (1st law)

Question 39

Does the total amount of energy in an isolated system change over time? Why or why not?

Answer 39

No, not free to exchange energy or matter with its surroundings. So, the total amount of energy remains constant.

Question 40

How did the discovery that mass is a form of energy resolve the debate over Earth’s age?

Answer 40

Kelvin calculated time earth too cool to present temperature based on rate energy radiated out into space

Found out rocks have radioactive elements. Thermal energy is generated by the conversion of mass as they decay

Question 41

Imagine an everyday situation in which you could use the word “power.” For instance, consider a basketball player about whom a commentator might say, “She showed a lot of power on that drive to the hoop!” How is this use of the word “power” the same or different from the scientifically accepted definition?

Answer 41

A body which has more energy= more power

A body which has less energy= less power

Science

Bod with less energy if does work at higher rate will have more power compared to the body containing higher energy

Question 42

How are coal and oil forms of solar energy?

Answer 42

Come from dead organisms

Plants use photo synthesis

Animals eat plants

OG source of energy is from the sun

Question 43

Ancient human societies are described as labor intensive, while modern society is said to be energy intensive. What is meant by these terms?

Answer 43

Labor intensive- humans did the work

Energy intensive- more machines do the work that run on fossil fuels or electricity