Post on 13-Jan-2016
LecturePLUS Timberlake 1
Chapter 2Energy and States of Matter
Energy
Measuring Temperature
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Energy
• Makes objects move
• Makes things stop
• Energy from sun plants foods we eat energy to
live
• We need energy to “do work”
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Work is done when
Go up stairs
Play soccer
Lift a bag of groceries
Ride a bicycle
Breathe
Heart pumps blood
Water goes over a dam
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Potential Energy
Is stored energy
Examples
Water behind a dam
Compressed spring
Chemical bonds in gasoline or coal
Food
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Kinetic Energy
Is energy of motion
Examples
Hammering a nail
Water flowing over a dam
Working out
Boxing
Burning gasoline
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Some Forms of Energy
Mechanical
Electrical
Thermal (heat)
Chemical
Radiant (light)
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Temperature
Particles are always moving.
When you heat water, the water molecules
move faster.
When molecules move faster, the substance
gets hotter.
When a substance gets hotter, its
temperature goes up.
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Learning Check E2
Suppose you place water in a freezer.A. The water particles move
1) faster 2) slower 3) the same
B. The water will get
1) hotter 2) colder 3) stay the same
C. The temperature of the water will be
1) higher 2) lower 3) the same
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Temperature
Measures the hotness or coldness of an
object
Determined by using a thermometer that
contains a liquid that expands with heat
and contracts with cooling.
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Temperature Scales
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Temperature Scales
Fahrenheit Celsius Kelvin
Water boils 212°F 100°C 373 K
Water freezes 32°F 0°C 273 K
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Units of Temperature between Boiling and Freezing
Fahrenheit Celsius Kelvin
Water boils 212°F 100°C 373 K
180° 100°C 100K
Water freezes 32°F 0°C 273 K
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Learning Check E3
A. Temperature of freezing water
1) 0°F 2) 0°C 3) 0 K
B. Temperature of boiling water
1) 100°F 2) 32°F 3) 373K
C. Number of Celsius units between the
boiling and freezing points of water
1) 100 2) 180 3) 273
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Fahrenheit Formula
180°F = 9°F = 1.8°F 100°C 5°C 1°C
Zero point: 0°C = 32°F
°F = 9/5 T°C + 32
or
°F = 1.8 T°C + 32
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Celsius Formula
Rearrange to find T°C
°F = 1.8 T°C + 32
°F - 32 = 1.8T°C ( +32 - 32)
°F - 32 = 1.8 T°C
1.8 1.8
°F - 32 = T°C
1.8
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Temperature Conversions
A person with hypothermia has a body temperature of 29.1°C. What is the body temperature in °F?
°F = 1.8 (29.1°C) + 32 exact three sig figs exact
one decimal= 52.4 + 32
= 84.4°F one decimal
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Learning Check E4
The normal temperature of a chickadee is 105.8°F. What is that temperature in °C?
1) 73.8 °C
2) 58.8 °C
3) 41.0 °C
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Solution E4
3) 41.0 °C
Solution:
°C = (°F - 32)
1.8
= (105.8 - 32)
1.8
= 73.8°F
1.8° = 41.0°C
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Learning Check E5
Pizza is baked at 455°F. What is that in °C?
1) 437 °C
2) 235°C
3) 221°C
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Solution E5
Pizza is baked at 455°F. What is that in °C?
2) 235°C
(455 - 32) = 235°C
1.8
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Learning Check E6
On a cold winter day, the temperature falls to -15°C. What is that temperature in °F?
1) 19 °F
2) 59°F
3) 5°F
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Solution E6
3) 5°F
Solution:
°F = 1.8(-15°C) + 32
= -27 + 32
= 5°F
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Kelvin Scale
On the Kelvin Scale
1K = 1°C
0 K is the lowest temperature
0 K = - 273°C
K °C
K = °C + 273
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Learning Check E7
What is normal body temperature of 37°C in kelvins?
1) 236 K
2) 310 K
3) 342 K
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Solution E7
What is normal body temperature of 37°C in kelvins?
2) 310 K
K = °C + 273
= 37 °C + 273
= 310. K