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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