Do Now • On your Daily Organizer, answer the following questions under Do Now. • We defined temperature as “simply the reading on a thermometer”. Based on the lesson Monday, what is one other good but not complete definition of temperature? • What is heat? • Give an example of a transfer of energy through heat.
Important Dates & Reminders • Quiz Friday • 5 multiple choice questions over temperature & heat • Homework Should Be In Bin • Lab Notebooks Due Next Friday • Homecoming Week • Today is CELEBRITY DAY!!! • Also, come to the Teacher vs. Student Game • Teachers WILL win
What is Temperature? • Temperature is simply the reading on a thermometer. • Other good but not complete definitions: • The degree of hotness or coldness of a body or environment. • A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale.
What does temperature measure? • Temperature is a measure of the average kinetic energy of the particles within a sample of matter. • When the temperature of an object increases, the particles that compose the object begin to move faster. • They either vibrate more rapidly, rotate with greater frequency or move through space with a greater speed. • A thermometer is kind of like a speedometer!
Temperature vs. Heat Temperature Heat • Measure of the hotness/coldness and the kinetic energy • Transfer of energy from hot object to cold object
Closer Look at Heat • What We Know • Heat is the transfer of energy from one thing to another because of a temperature difference (one is considered hot and one is considered cold) • Nothing actually HAS heat – everything has kinetic energy. Heat is the energy that is being transferred. • Heat never flows from cold to hot. It always flows from HOT TO COLD. • What We Need to Find Out • How much heat is transferred • Depends on temperature difference and amount of material
Quantity of Heat The unit of heat is defined as the energy necessary to produce some standard change. The most commonly used unit for heat is the calorie.
Calorie • The calorie is defined as the amount of heat required to change the temperature of 1 gram of water by 1 Celsius degree. • What you see on the ratings of food and at the gym is actually measured in kilocalories. • Since we know that heat is a form of energy, what is the unit we usually use to measure energy?
Calorie • The calorie is defined as the amount of heat required to change the temperature of 1 gram of water by 1 Celsius degree. • What you see on the ratings of food and at the gym is actually measured in kilocalories. • Since we know that heat is a form of energy, what is the unit we usually use to measure energy? • Joules • 1 calorie = 4.187 J
So what does heat do? • Heat changes the temperature of objects. • If heat is transferred from an object to the surroundings, then the object can cool down and the surroundings can warm up. • When heat is transferred to an object by its surroundings, then the object can warm up and the surroundings can cool down. • Heat affects the kinetic energy of the objects because it changes the temperature.
Specific Heat Demos Before we go into what exactly the definition of specific heat is, I am going to perform a couple demonstrations for you to start the thinking process. Make your predictionsof what you think will happen!
Specific Heat • Have you ever noticed that some foods stay hotter much longer than others? • Different substances have different abilities to store energy. • The specific heat of a substance is defined as the quantity of heat required to change the temperature of a unit of mass (like a gram or kilogram) of the substance by 1 degree. • Metric Units: Joules/kilogram*Kelvin (J/kg*K). • More commonly used units: J/g*°C.
Specific Heat Example • The specific heat capacity of solid aluminum (0.904 J/g/°C) is different than the specific heat capacity of solid iron (0.449 J/g/°C). • Which one has a greater specific heat capacity?
Specific Heat Example • The specific heat capacity of solid aluminum (0.904 J/g/°C) is different than the specific heat capacity of solid iron (0.449 J/g/°C). • Which one has a greater specific heat capacity? • Aluminum • This means that it would require more heat to increase the temperature of a given mass of aluminum by 1°C compared to the amount of heat required to increase the temperature of the same mass of iron by 1°C.
Specific Heat Demo Analysis Now that we know more about what specific heat is, we can explain why the dollar bill did not burn and why the balloon with air popped first.
Exit Ticket • Exit tickets are my daily way of seeing whether or not you have understood the objectives we have gone over during class each day. • They are NOT be graded for accuracy but WILL be graded for completion so make sure you always try each and every question. • These exit tickets must be done silently and independently. If you violate this, you will lose your participation points for the day.