How do we measure how hot or cold an object is Temperature Temperature is a measure of how hot an object is Thermometers A long glass tubed closed at both ends Contains either alcohol or mercury ID: 642618
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Slide1
Temperature
Chapter 45 – Page 306Slide2
How do we measure how hot or cold an object is?Slide3
Temperature
Temperature is a measure of how hot an object is
Thermometers
A long glass tubed closed at both ends
Contains either alcohol or mercury
What happens to the liquid inside?Slide4
Thermometers
Liquid expands when heated
Contracts when cooledSlide5
Questions to make you think
F
oil
and the cotton towel are both at the same temperature – so why does the foil feel colder?
A candle needs oxygen to burn, which is why if we want to resuscitate a dying fire we blow on it.
So why does blowing on a candle put it out?
Why does it get colder as you climb up a mountain, even though you’re getting closer to the sun Slide6
Why might a glass crack when you pour boiling water into it?
If you lick a frozen pipe why will your tongue stick to the pipe?
Why are ice cubes much better at cooling a drink that the equal amount of iced water?
Why is a scald from steam much more serious that a burn from boiling water?Slide7
When stepping out of bed on a cold morning, why does it feel colder if your feet touch say, a marble floor rather than a floor with carpet even though both are at the same temperature
?
How
does perspiration (sweating) help to keep us cool?
Many Arabs wear dark clothing in warm weather, even though dark clothes are better at absorbing heat than white clothes. Any idea why?
Slide8
Is heat and temperature the same?
Think
Pair
Share
Imagine 2 hot water bottles, one half filled and the other full with boiled water. Which one will keep you warm for longer?Slide9
The amount of heat in a substance depends on its temperature, its mass, and what the substances are
Think about these tow scenariosSlide10Slide11Slide12
http://
www.youtube.com
/
watch?v
=yXT012us9ng&feature=
share&list=PLED25F943F8D6081CSlide13
Today we will…
Recap on states of matter
Look at the concept of latent heat\
Plot a temperature plot of ice changing to water vapor to demonstrate latent heatSlide14
Changes of State
What are the 3 states of matter?
How do we move from one state to another?Slide15
Change of State
Adding heat gives energy to the molecules allowing them to move faster
This increased movement changes the state from solid to liquid and then to gas
Removing heat means the molecules slow down and so change back from gas to liquid to solidSlide16
Phet AnimationSlide17
To Determine the Melting Point of IceSlide18
To Determine the boiling point of waterSlide19
“Hidden Heat”
What sort of a temperature graph do you think I would get from this scenario?Slide20
The experiment
Set up apparatus: Slide21
Method
Turn on hot plate and start recording temperature every minute
Do this until the water starts to boil
Record your results
Plot the point on graph paperSlide22
Results Table
Time (min)
Temperature (°C)
1
2
3
4
5
6
7
8
9
10Slide23
Latent Heat