{ Problem 1} 
What are the linear sizes of the following objects (in meters)?

Earth
cell 
atom 


{ Problem 2}
What are the velocities (in m/s) of:

the speed of light 
a snail at full speed 
An automobile on the highway 



Part II: estimation

State all of your assumptions clearly and show your reasoning.

 Do four  of the following six problems.  

{ Problem 1} How long will it take human respiration to use up 10% of
the atmosphere's oxygen, ignoring all other contributions?

{ Problem 2} How many cows are slaughtered daily so Americans can eat
beef?

{ Problem 3} How much energy is needed to get a spaceship from Earth
to Alpha Centauri (the nearest star, about 4 light-years away) before
the passengers die of old age?  The spaceship should finish its trip
at rest.  How much fuel will this take (assuming 10^{15} J/megaton of
TNT)?

{ Problem 4} How much energy of all kinds does the US use each year?
How does this compare to the food energy consumed by Americans?

{ Problem 5} How many pencils would it take to draw a line the length
of the Equator?


{ Problem 6} a) A steel ball is dropped from a height of 3 m onto a
concrete floor. It bounces a large number of times but eventually
comes to rest.  Estimate the ball's rise in temperature.  (b) Suppose
a nickel-iron meteor falls to the earth from deep space.  Estimate how
much its temperature would rise on impact.