Why gas-guzzling cars? Why is our transportation dominated by four
wheels powered by a gasoline-snorting engine?
People have been using wheels for nearly 6,000 years. The invention
of the wheel probably occurred many times in many places and no
event of inception was recorded. At first wheels were powered by the
people who made them. Hitching animals to move carts started around
4,000 years ago.
The power state of a laptop computer is usually difficult to determine, unless it is in use and obviously on.
A closed laptop has few external indicators, and those that are present are often ambiguous and inconsistent
(e.g., between brands or models). In terms of improving our estimates of laptop unit energy consumption,
the most relevant data is the amount of time each laptop spends plugged in, and how often its battery is
(re)charged. Therefore, we recorded, at a minimum, whether or not each laptop was plugged in.
In this report...
Today’s direct-injection diesel engines are more rugged, powerful, durable, and reliable than gasoline engines, and use fuel much more efficiently, as well. engines start the explosions with sparks from spark plugs, whereas in diesel engines, fuel ignites on its own. Air heats up when it’s compressed. This fact led German engineer Rudolf Diesel to theorize that fuel could be made to ignite spontaneously if the air inside an engine’s cylinders became hot enough through compression.