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 Book 1 Section 1.1 Temperature

Book 1 Section 1.1 Temperature Is heat wave coming? …it is believed that the temperature in New York will go up to 70 degrees this week… ? ? ? Which temperature scale is it referring to? 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? Book 1 Section 1.1 Temperature

1 Temperature–a measure of hotness To compare the hotness of objects, we need to measure their temperatures. Temperature is a measure of the degree of hotness of an object. Temperature can be measured in degrees Celsius (C). Book 1 Section 1.1 Temperature

1 Temperature–a measure of hotness Some different temperatures in Celsius temperature scale: Bunsen flame 1000 C surface of sun 5500 C melting ice 0 C human body 37 C Warm room 25 C boiling water 100 C bulb filament 2500 C Absolute zero –273 C Book 1 Section 1.1 Temperature

2 The Celsius temperature scale a Defining the Celsius temperature scale Celsius Scale: most commonly used 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 Book 1 Section 1.1 Temperature

a Defining the Celsius temperature scale Ice point  lower fixed point Steam point  upper fixed point (100C) Lower fixed point Upper fixed point . . . 100 divisions . . . . . . 1 division  1 degree (1C) Book 1 Section 1.1 Temperature

b Calibrating a thermometer on the Celsius temperature scale 1/100 of the interval = 1 C 0 °C 100 °C 2. Mark the liquid level 4. Mark the liquid level 3. Put in boiling water 1. Put in melting ice Book 1 Section 1.1 Temperature

b Calibrating a thermometer on the Celsius temperature scale Let’s begin 1.1 Calibration of thermometer (liquid-in-glass) Simulation Calibrating a liquid-in-glass thermometer Example 1 Book 1 Section 1.1 Temperature

Book 1 Section 1.1 Temperature Check-point 1 – Q1 Which of the following about the Celsius scale is incorrect? A Lower fixed point = 0 C Upper fixed point = 100 C 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. Book 1 Section 1.1 Temperature

Book 1 Section 1.1 Temperature Check-point 1 – Q2 The calibration graph of a thermometer: 15 cm 60 C When T = 60 C, L = _______. 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. Particles attract/repel each other close particles distant particles weak attraction strong attraction Book 1 Section 1.1 Temperature

3 Temperature and particle motion Particles of... solid liquid gas fixed volume and shape fixed volume but irregular shape irregular volume and shape very close  strong attraction less close  strong attraction far apart  weak attraction Book 1 Section 1.1 Temperature

3 Temperature and particle motion solid liquid gas 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 Book 1 Section 1.1 Temperature

3 Temperature and particle motion Temperature of an object is a measure of the average K.E. of its particles. T   particles vibrate more rapidly or move faster T   particles slow down same average K.E.  same temp average K.E. is minimum  absolute zero Book 1 Section 1.1 Temperature

Book 1 Section 1.1 Temperature Check-point 2 – Q1 Tommy says: ‘This object is extremely cold!’ Which of the following cannot be the temp of the object? A –300 C No temperature can be lower than absolute zero (–273 C)! B –30 C C 0 C D 3 C Book 1 Section 1.1 Temperature

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 Book 1 Section 1.1 Temperature

Book 1 Section 1.1 Temperature The End Book 1 Section 1.1 Temperature