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Things to ponder Why does it take Lake Sammamish so long to warm up? How do fireworks work? What are you feeling when you feel warm? What is energy? What.

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Presentation on theme: "Things to ponder Why does it take Lake Sammamish so long to warm up? How do fireworks work? What are you feeling when you feel warm? What is energy? What."— Presentation transcript:

1 Things to ponder Why does it take Lake Sammamish so long to warm up? How do fireworks work? What are you feeling when you feel warm? What is energy? What is heat? What is the difference between them?

2 What is heat? What is temperature? What is the difference between heat and temperature?

3 What does temperature measure? The rate of movement of atoms and molecules

4 If temperature is a measure of the speed of molecules, Then, what is HEAT? Which has more heat? one drop of water at 100 ⁰ C or one cup of water at 100 ⁰ C

5 While temperature is a measure of the speed of molecules, Heat is a measure of the quantity of energy present. Heat is a form of Energy.

6 What do you think will happen to the temperature of water when I add the same mass of boiling water to it? Why? What will happen to the temperature of water when the same mass of metal is added to it? Why is the temperature change different with a metal than water? Q(water)=s(water)m(water)∆t Q= Energy required M=Mass of object ∆t= Change in temperature What do you think s is???

7 How can scientists measure the amount of heat that is contained in something? You measure by transfer of energy from a hot object to a cooler object.

8 A calorimeter is an instrument that measures heat by the transfer of energy.

9 One unit of energy is the calorie: What is the definition of a calorie? The amount of energy needed to raise the temperature of 1.0 gram of water 1.0 degree Celcius. Chemists don’t use calories. Instead, we use the unit joule. One calorie equals 4.184 joules

10 Specific Heat The specific heat measures how much energy one gram of a substance absorbs before its temperature increases one degree Celcius. Every pure substance has its own unique specific heat

11 In summary, to measure energy transferred, Q, we must record the following things in the absorbing medium: –Change in temperature in degrees Celcius: ∆T –Mass of the medium: m –Specific heat of the medium in Joules/ gram: S Q = Sm∆T

12 Can we determine the amount of energy transferred in the water? We need specific heat S= m* ∆t S= Q m* ∆t S= The amount of energy it requires to raise 1 g of water 1 degree C The specific heat of water is 4.184 J g*C g*C How much energy was added to the to the water?

13 How could we determine the specific heat of a washer (an unknown metal)? Keep in mind the amount of energy is never lost just transferred. What do you think?

14 Could you determine the amounts of another metal? How?


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