1.1 Temperature : Book 1 Section 1.1 Temperature Is heat wave coming?
Temperature—a measure of hotness
The Celsius temperature scale
Check-point 1
Temperature and particle motion
Check-point 2 1 2 3 1.1 Temperature
Is heat wave coming? : Book 1 Section 1.1 Temperature Is heat wave coming? Which temperature scale is it referring to? …it is believed that the temperature in New York will go up to 70 degrees this week… ? ? ?
1 Temperature–a measure of hotness : Book 1 Section 1.1 Temperature 1 Temperature–a measure of hotness Hot pot Ice-cream We can feel different degrees of ‘hotness’ from different objects. How to compare their hotness accurately?
1 Temperature–a measure of hotness : Book 1 Section 1.1 Temperature Temperature is a measure of the degree of hotness of an object. 1 Temperature–a measure of hotness To compare the hotness of objects, we need to measure their temperatures. Temperature can be measured in degrees Celsius (C).
1 Temperature–a measure of hotness : Book 1 Section 1.1 Temperature 1 Temperature–a measure of hotness Some different temperatures in Celsius temperature scale:
2 The Celsius temperature scale : Book 1 Section 1.1 Temperature 2 The Celsius temperature scale a Defining the Celsius temperature scale Defined by choosing two fixed points: 1. Ice point: temp of pure melting ice at normal atm pressure
2. Steam point: temp of steam over pure boiling water at normal atm pressure Celsius Scale: most commonly used scale
a Defining the Celsius temperature scale : Book 1 Section 1.1 Temperature a Defining the Celsius temperature scale Ice point lower fixed point Steam point upper fixed point . . . 100 divisions . . . 1 division 1 degree (1C) (100C) (0C)
b Calibrating a thermometer on the Celsius temperature scale : Book 1 Section 1.1 Temperature b Calibrating a thermometer on the Celsius temperature scale 1/100 of the interval = 1 C 2. Mark the liquid level 3. Put in boiling water 1. Put in melting ice 4. Mark the liquid level 0 °C 100 °C
b Calibrating a thermometer on the Celsius temperature scale : Book 1 Section 1.1 Temperature b Calibrating a thermometer on the Celsius temperature scale Let’s begin Example 1 Calibrating a liquid-in-glass thermometer Simulation 1.1 Calibration of thermometer (liquid-in-glass)
Example 1 : Book 1 Section 1.1 Temperature Length of liquid (L) in an unmarked thermometer varies with temperature (T ). T = 0 C, L = 5.0 cm
T = 100 C, L = 25.0 cm Example 1 Calibrating a liquid-in-glass thermometer (a) Draw the calibration graph. (b) In warm water, L = 13.0 cm What is the temperature of water?
Example 1 : Book 1 Section 1.1 Temperature Example 1 (a) Plot a calibration graph: Calibrating a liquid-in-glass thermometer × × When T = 0 C, L = 5 cm When T = 100 C, L = 25 cm
Example 1 : Book 1 Section 1.1 Temperature Example 1 (b) Method 1: Graphical method Calibrating a liquid-in-glass thermometer Warm water is at 40 C. Since L = 13.0 cm, 13 cm
Example 1 : Book 1 Section 1.1 Temperature Example 1 T = 0 C, L = 5.0 cm
T = 100 C, L = 25.0 cm (b) Method 2: By proportion 100 divisions between 5.0 cm & 25.0 cm Temp of warm water = 13.0 – 5.0 25.0 – 5.0 100 = 40 C Calibrating a liquid-in-glass thermometer
Check-point 1 – Q1 : Book 1 Section 1.1 Temperature Check-point 1 – Q1 B (upper fixed point – lower fixed point)/100 1 division = 1 degree Celsius C It is the only temp scale available. D T > 100 C and T < 0 C are possible. A Lower fixed point = 0 C Upper fixed point = 100 C Which of the following about the Celsius scale is incorrect?
Check-point 1 – Q2 : Book 1 Section 1.1 Temperature Check-point 1 – Q2 The calibration graph of a thermometer: When T = 60 C, L = _______. 60 C 15 cm
3 Temperature and particle motion : Book 1 Section 1.1 Temperature 3 Temperature and particle motion Kinetic Theory: All matters are made up of tiny particles which are constantly in motion. close particles strong attraction distant particles weak attraction Particles attract/repel each other
3 Temperature and particle motion : Book 1 Section 1.1 Temperature 3 Temperature and particle motion very close strong attraction Particles of... less close strong attraction far apart weak attraction fixed volume and shape fixed volume but irregular shape irregular volume and shape
3 Temperature and particle motion : Book 1 Section 1.1 Temperature 3 Temperature and particle motion fixed positions; can vibrate only no fixed positions; can change position no fixed positions; move at very high speeds in random motion Simulation 1.2 Models of solid, liquid and gas
3 Temperature and particle motion : Book 1 Section 1.1 Temperature T particles vibrate more rapidly or move faster T particles slow down 3 Temperature and particle motion same average K.E. same temp Temperature of an object is a measure of the average K.E. of its particles. average K.E. is minimum absolute zero
Check-point 2 – Q1 : Book 1 Section 1.1 Temperature Check-point 2 – Q1 B –30 C C 0 C D 3 C A –300 C Tommy says: ‘This object is extremely cold!’ Which of the following cannot be the temp of the object? No temperature can be lower than absolute zero (–273 C)!
Check-point 2 – Q1 : Book 1 Section 1.1 Temperature Check-point 2 – Q1 Which of the following is incorrect? A Gas particles are far apart and move at very high speeds. B Temp rises particles move faster C Temp is a measure of total KE D Same temp particles have same average KE
The End : Book 1 Section 1.1 Temperature The End