IB Physics HL Topic 8

Primary energy source

Energy used directly by the consumer (Ex: Coal in stove to make heat, water turning wheel to grind flour)

Secondary energy source

Energy source that has transformed from a primary source (Ex: Electricity(transformed from coal/water/solar/wind/etc.))

Specific energy(Esp)

Energy per unit mass

Specific energy equation(Esp)

Esp=Energy/Mass

Energy density(Ed)

Energy per unit volume

Energy density equation

Ed=energy/volume

Energy density and specific energy relationship

Ed = Esp*D

Energy Degradation

Energy Lost during converison

Efficiency

efficiency = output power/input power

Sankey diagrams

A 'to scale' diagram representing energy transfers

Solar photovoltaic energy

Takes in suns energy and converts it to electricity

Solar photovoltaic energy(pro & con)

Pro: Renewable, No GHG

Con: Not reliable(only works in sunny conditions)

Hydroelectric energy

Water from reservoir comes into damn through turbines creating energy

Hydroelectric energy (pro & con)

Pro: renewable, no GHG


Con: Enviormental(habitat) concerns

Geothermal energy

Uses steam(mined from hot springs beneath the earths surface) to turn turbines to produce electricity.

Geothermal Energy (pro & con)

Pro: available 24/7, no GHG


Con: noise pollution, habitat concerns and can cause earthquakes

Biomass energy

When organic material is burned to produce electricity or heat

Biomass energy (pro & con)

Pro:renewable and reduces waste

Con: expensive, uses lots of land, habitat loss and GHG(from burning) concerns

Biofuel Energy

Two main types are ethanol and biodiesel, renewable energy substitutes for gas and diesel in combustion.

Biofuel energy (pro & con)

Pro: Lower GHG(then coal and gas and diesel)

Con: expensive, high water, food, and land demand, and can damage soil.

Natural gas

product of organic molecular breakdown over time within the earths crust from pressure and breakage of bonds to produce natural gas.

Natural Gas (pro & con)

Pro:reliable, cheap and easy to get


Con: not renewable, lots of GHG, Enviormental damage

Coal energy

Burned to produce energy(steam turns turbine)

Coal energy (pro & con)

Pro: easy and cheap to obtain

Con: lots of GHG, not renewable

Tidal Energy

Utilizes highs and lows of tides to produce energy. traps water at high tide and lets it go through turbines at low tide to produce energy(mgh)

Tidal Energy (pro & con)

Pro: renewable, no GHG

Con: only works in water, habitat concerns

Solar Thermal energy

absorbs sunlight to heat your house/building/thing

Solar Thermal energy (pros & cons)

Pro: renewable, no GHG

Con: costly, only works during the day

Wind Power

Using wind to turn a turbine to generate electricity

Wind power (pros & cons)

Pro: no GHG, renewable, free air

Con: not dependable(location dependent), low power input, habitat concerns, expensive

Power equation(general)

Power = energy/time

Power Wind turbine

P=1/2A(density)V^3 OR P= 1/2(pi*r^2)(density)v^3

Nuclear Fission

when an unstable nuclear splits into smaller parts after a collision, producing energy and free neutrons

What starts Nuclear Fission

Slow neutrons with low energy that collide with unstable nuclei

What allows collision to occur

Moderator- absorbs kinetic energy of neutrons to slow them down and allow more reactions to take place

What controls reactions

Control Rods- Absorbs excess 'free neutrons' to control chain reactions(rods in deeper mean slower, rods in shallower means faster reactions)

Nuclear Fission (pro & con)

Pro: high "specific energy", lots of uranium stockpiled, no GHG

Con: lots of waste never goes away, Enviormental risk, nonrenewable

Conduction

When thermal energy is transferred by molecular interaction
Ex: Ice in hot cup of tea

Convection

When thermal energy moves from one point to another by molecular movement(only occurs in liquids)
Ex: Water being heated

Radiation

When thermal energy is transferred via electromagnetic waves(no molecular movement or interaction required)
Ex: any object that is giving off heat
ALL OBJECTS EMIT RADIATION

Blackbody

An idealized body that is a perfect absorber and emitter of energy

In blackbody graph: (x and y axis?)

x-axis- Wavelength
Y-axis- Intensity

In a blackbody graph: Higher temp means peak intensity occurs at _____

Lower wavelengths

In a blackbody graph: Higher temp means _____ peak intensity

higher

Stefan Boltzman Law equation

P=𝞂AT^4 (Must be in kelvin)

Intensity equation

Intensity = 𝞂T^4

Emissivity(e)

ratio that tells us how close a body is to being a perfect blackbody

Emissivity(e) equation

e = emitted power/emitted power by black body at same temperature

Albedo(a)

fraction of radiation that is reflected

Albedo(a) Equation

a= total reflected power/total incidence power

Earths Atmosphere serves as a ....

shield, blocking out harmful radiation

Earths Atmosphere traps....

inferred radiation(heat) that radiates out form the earths sun warmed surface

More CO2 means more___ in atmosphere

infrared radiation

Methane and Carbon dioxide "wiggle' which means they

absorb heat