Complete the following on your own Sig Fig Question 6849 23 234 2679 x 089 Scientific Notation Question 000000032 7692834023 Hand In When Done Solar Cells composed of 2 layers of silicon one with phosphorus one with boron ID: 553581
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Slide1
Seat Work:
Complete the following on your own
Sig Fig Question:
684.9 + 23. 234 =
2.679 x 0.89 =
Scientific Notation Question:
0.00000032 =
7692834.023 =
Hand In When Done!Slide2
Solar Cells
composed of 2 layers of silicon (one with phosphorus, one with boron)
When light hits the layers, it causes electrons to break free from the silicon
phosphorus layer = becomes negativeboron layer = becomes positivePoles are created and electricity is made (flowing of electrons)Slide3
Fuel Cells: hydrogen fuel cells operate like a
battery
Convert
chemical energy in hydrogen into electrical energyDoes not need recharging – needs fuel (water & heat) to work It is popular in
spacecraft'sSlide4
Theories of Heat
Section 3.1Slide5
What is heat??Slide6
Early Theories of Heat
Theory of the 4 Elements
Approx. 450 BC
All matter consists of some combination of earth,
air
,
fire
, and
water
Many objects contain fire, and when they burn fire is releasedSlide7
Early Theories of Heat
Theory of the 4 Elements
Approx. 450 BC
All matter consists of some combination of earth,
air
,
fire
, and
water
Many objects contain fire, and when they burn fire is released
Phlogiston
Theory
Early 1700s
Substances that burn contain an invisible liquid called Phlogiston that flows out when burned
Slide8
Early Theories of Heat
Theory of the 4 Elements
Approx. 450 BC
All matter consists of some combination of earth,
air
,
fire
, and
water
Many objects contain fire, and when they burn fire is released
Phlogiston
Theory
Early 1700s
Substances that burn contain an invisible liquid called Phlogiston that flows out when burned
Calori
c Theory
Late
1700s
Caloric (heat) is a mass-less substances found in all substances
Caloric flows from warmer to cooler objects
1 Calorie = amount of Caloric needed to increase the temperature of 1 g of water 1
o
CSlide9
Modern Theories of Heat
Count Rumford’s Hypothesis
1780s
While making a cannon, the tools
and metal became very hot.
This did not
make sense with the
Caloric Theory
Rumford suggested ‘caloric’ (the
mass-less substance)
did not exist
and that the mechanical energy being
exerted on the cannon and tools was
being converted to heat Slide10
Modern Theories of Heat
Julius Mayer’s Hypothesis
1840s
Doctor
Suggested heat was related to
energy
Proposed that energy from food
was used to do physical work and
to heat the body
Because he wasn’t schooled in
math/physics, his ideas weren’t accepted
Despite his work, James Joule was given credit for discovering the mechanical equivalent of heat Slide11
Modern Theories of Heat
James Joule
Late 1800s
Conducted numerous experiments to determine
the mechanical equivalent of heat
Measured the force that gravity exerts on the weight and the distance the weight fell
From this he determined the work done on the
water and
related it to temperature Slide12
3.2:
The Development of Steam Engines
A
steam engine is …
….any
machine that generates steam and converts the steam pressure into mechanical motion.Slide13
The First “Steam Engine”
Hero
of Alexandria
(Greek inventor) invented the first “steam engine” sometime between 130 B.C. and 70 A.D.
It was really only a toy, since it didn’t have any practical purpose.Slide14
The F
irst
Practical
Steam Engine… Were developed in the 1600’s. Designed
to remove water from coal mines. Slide15
The
Savery
Steam Engine
Thomas Savery of England
built
the
first practical machine to
pump
water from
coalmines
(
patented
in
1698).
V
ery inefficient and
costly
to operate. Relied on atmospheric pressure to push the water out of the mine.Slide16
The Newcomen
Steam Engine
Designed an atmospheric
engine
in 1712.
Big
improvement
from
Savery’s
engine.
-
Did not
have to open valves
manually
.
Used atmospheric pressure to push the piston downAlso used atmospheric pressure to pump water out of mines.Engine wore out quickly due to constant heating and cooling of parts.Slide17
The ‘Double Acting’ Steam Engine
Invented by
James
Watt in 1796Was the model for all steam engines for years to come.Slide18
The ‘Double Acting’ Steam Engine
Steam is
condensed by a spray of water in a separate chamber.
This causes engine parts to always be hot,
so they
last
longer.
Watt designed
a system of gears and levers so the piston could turn a wheel. This provided power for many
industries
.Slide19
Steam
Engines
and the
Industrial RevolutionWatt’s steam engine was responsible for the rapid development of the Industrial Revolution
, which began in the late 1700’s
.
Powered machines in flourmills,
saw
mills, and textile factories
.
Steam powered tractors were
used
to produce food for the
growing
populations
.
Steam powered locomotives and
paddle-wheel steamboats were developed to transport people and suppliesSlide20
Steam Turbines
Designed in 1884
Steam-Turbine Engines
are used to power giant ocean liners and cruise ships
.
Steam turbine engines
do not
use pistons; they use
curved blades
similar to fan blades.
Modern turbines use several rotors and several sets of stationary blades.Slide21
Scientific Notation
978429432.02 =
0.0000000000002183 =