Clicker Question
Around 1.5 billion years ago, the Oxygen content of
the atmosphere increased significantly to close to its
current level of 21%.
What caused this increase?
A)
B)
C)
D)
E)
Cooling of the molten core of the Earth
Giant impact with the Earth that created the Moon
Early advanced mammals burning wood
Organisms capable of photosynthesis
Increased volcanic activity on the Earth
Why might astro-biologists find this interesting?
Reading Assignment
For today, January 20, 2017 read all of Chapter 1 (short)
Also, push ahead and read Chapter 2 (all sections by Monday)
* Note that Chapters 1 & 2 are scanned and on D2L.
Homework Assignment
Homework Assignment #1 is available
and due next Wednesday, January 25, 2017 @ 4:30 pm.
-- I am available all next week, so email me and come talk to me
about any concerns and specific topics you want to cover…
Regular Office Hours Mondays 11 am – 12 pm
-- Next week the class Teaching Assistants will also be available in
the Physics Help Room (downstairs on the Duane 2B level).
Phil : Mondays 2 - 3 pm; Joanna : Wednesdays 9 -10 am
Dushyant: Wednesdays 11 am -12 pm; Andrew: Wednesdays 2–3 pm
When reading the first few Chapters,
think about the challenges related to energy storage
Basketball Cannon
Demonstration
Energy and Power
Energy density of
different materials or
battery technologies
have a big impact on
how they are utilized.
Each person can deliver Energy at a rate per unit Time of
about 100 Joules / second which is a Power of 100 Watts.
We are going to need these units and keep the concepts of
Energy and Power clear to do real calculations.
1
Each one of us is like a “100 Watt” light bulb.
Another unit of Power is the horsepower (hp).
1 hp = 746 Watts
This rough number can be used to calculate the
air conditioning capacity needed for a lecture
hall assuming a given outside temperature.
Another unit of Power is the horsepower (hp).
1 hp = 746 Watts
How many Watts does this truck deliver (i.e. Joules / second)?
A) 0.5 Watts
B) 10,000 Watts
C) 300,000 Watts
D) 1,000,000 Watts
E) Impossible to determine
 746W
360hp  
 1hp
 746W
360hp  
 1hp

  268,560W


  268,560W  2.68 105W

Always good to ballpark check your answer…
e.g. 300 x 800 = 24 x 100 x 100 = 2.4 x 105
It is amazing what you catch just by
looking for obviously wrong answers.
We get our Energy input from eating food.
Food Calorie is another unit of Energy.
“Hitting the Wall” or the “Bonk” –
“In endurance sports such as cycling and running, hitting
the wall or the bonk describes a condition caused by the
depletion of glycogen stores in the liver and muscles, which
manifests itself by sudden fatigue and loss of energy”
https://en.wikipedia.org/wiki/Hitting_the_wall
Clearly our usage of energy / time or power is
much greater than we individually supply.
We get our energy elsewhere to heat our houses, run our
cars, build our smart phones and right now the world gets
85% of that from fossil fuels.
Clicker Question
Why does this look different from the previous graph?
What percentage of U.S. Electricity comes from wind energy?
A) 0.05% B) 0.5% C) 5.0% D) 50.0% E) 500.0%
Watch out for memorizing numbers – easy to confuse percentage
of world electricity vs. US electricity,
or US energy total vs US electrical energy
Oil is a much bigger player? Why?
This is total energy, previous graph was just electricity!
2
Age of Fossil Fuels
What is this graph telling us?
How can we verify that it is accurate?
3