Ch 3 Textbook/ slides Flashcards
Power eqt w/ units
Power (watts)= work (J)/time (s)
Power (watts)= Energy (J) /time (s)
Power: Measure of
The amount of _ done or _ expended
The amount of _ it takes to do that _
Power: Measure of
The amount of work done or energy expended
The amount of time it takes to do that work
Power and energy: Energy eqt
Energy (joules)= power (watts) x time (seconds)
Describe energy changes during bungee jump
- Energy to top
- where does PE come from
- fall
- bounce
- 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.
Name the trophic levels (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
Describe energy loss between trophic levels and why
- 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
First law of thermodynamics
In an isolated/closed system, the total amount of _, including _ , is conserved
First law of thermodynamics
In an isolated/closed system, the total amount of energy, including heat , is conserved
why
Whole grains cost 1/10th of meat
It takes 10 times as much energy to make the 1 lb of beef than 1 lb of wheat
why dinos warm blooded
- 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
why earth and sun closed system
No significant amount of energy or matter are being added from outside sources
difference between kcal and cal
- 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
You consume _ calories to gain a lb of fat
You consume 3500 calories to gain a lb of fat
maintain weight eqt
lose weight eqt
To maintain your weight
- X lbs * 15 calories/lb
Lose pounds
- 3500 calories/ x days= # calories reduce your diet by
How did the discovery that mass is a form of energy resolve the debate over Earth’s age?
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
the growth of modern technological societies since the Industrial Revolution has been driven by the availability of _ and _ sources of energy
the growth of modern technological societies since the Industrial Revolution has been driven by the availability of cheap and high-grade sources of energy
us #1 source of E
2 probs
1 petroleum
2 problems
- Fossil fuels are not replaceable
- Adds CO2 to the atmosphere- lead to global warming
1 (2)
US alt energy
Alt energy
Biomass collectively #1
Hydropower #1 alone
describe 3 gens of biomass
1st-edible
2nd- non edible
3rd-algae
1 source-
Freshwater withdrawals
When economy goes down so does __
1 source- surface water
Freshwater withdrawals
When economy goes down so does __
hydroelectric power can meet total energy demand of in western states t/f
true
Use less water- thermoelectric
New power plants converted to water efficient__
Decrease use in _
Increase use of _
Closing plants with _ cooling systems
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
base load vs peak
- what supplies elect
- where alt energy
- base= daily
- Coal/ nuclear plants
- peak= extra
- Gas turbinesCheap to build, but expensive to operate
- More expensive fuels
- Alt energy peak-comparable cost
t/f all US energy can be generate from wind
true
problem w/ ethanol
solution?
- Made form corn kernels
- Competes with corn as a food for humans and animals
- Cellulosic ethanol (2nd gen)
2 major problems w renewables
- intermittent
- need storage system
__ of US energy budget is spent on transportation
1/3
pros and cons of electric cars
Pro
- Less fossil fuel use
Con
- Water used in electric generation
- Converting chemical to electrical energy.. There is energy loss
Prescott Joule is noted in science for his discovery that
_ (mechanical energy) could be transformed into _
Prescott Joule is noted in science for his discovery that
motion (mechanical energy) could be transformed into heat
As work is performed on the planet Earth, some energy is lost in the form of
Heat
The energy balance of the earth means
the amount of solar energy absorbed by Earth equals the amount of heat energy radiated from Earth minus the work done
Energy can be stored in a flashlight battery as
chemical potential energy
In place of the kilowatt, a metric unit, the English system uses the unit
kw= Horse power
Energy can be defined as
The ability to do _
F*_
Work
Power*_
Energy can be defined as
The ability to do work
F*d
Work
Power (watts= J/s)*t
The rating of a light bulb at 100 watts indicates
the rate of energy that the bulb consumes
What is the difference between energy and power? What is a unit of power?
Energy= ability to do work
Power= rate work is done or rate energy is consumedUnit
P=W/t
Watts=Joules/seconds
What is the relationship between heat, energy, and the motion of atoms?
All atoms are in constant motion (KE)
Faster moving atoms= posses more thermal energy
Explain how sound is actually a form of energy. In what medium do sound waves travel?
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.
What does it mean to say that different forms of energy are interchangeable?
We mean that total energy content of system remains constant (1st law)
Does the total amount of energy in an isolated system change over time? Why or why not?
No, not free to exchange energy or matter with its surroundings. So, the total amount of energy remains constant.
How did the discovery that mass is a form of energy resolve the debate over Earth’s age?
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
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?
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
How are coal and oil forms of solar energy?
Come from dead organisms
Plants use photo synthesis
Animals eat plants
OG source of energy is from the sun
Ancient human societies are described as labor intensive, while modern society is said to be energy intensive. What is meant by these terms?
Labor intensive- humans did the work
Energy intensive- more machines do the work that run on fossil fuels or electricity
