Solid Gas Liquid INTERNAL ENERGY, U   Every object of matter, whether solid, liquid, or gas, consists of atoms or molecules in rapid motion. The kinetic energies of these particles constitute the internal energy of the body of matter. Solid Gas Liquid

Heat Q, may be thought of as internal energy in transit Heat Q, may be thought of as internal energy in transit. When heat is added to a body, its internal energy increases and its temperature rises; when heat is removed from a body, its internal energy decreases and its temperature falls.

A thermometer is a device for measuring temperature.   Temperature is familiar as the property of a body of matter responsible for sensations of hot or cold to the touch. Temperature indicates the direction of internal energy flow: When two objects are in contact, internal energy goes from the one at higher temperature to the one at lower temperature. The temperature of the body is a measure of the average kinetic energy of its particles. A thermometer is a device for measuring temperature.

Temperature and Thermometers Thermometers make use of physical properties that change with temperature. Many physical properties can be used: volume of a liquid length of a solid pressure of a gas held at constant volume volume of a gas held at constant pressure electric resistance of a conductor color of a very hot object Thermometers work by quickly getting to the same temperature as its surroundings Temperature is a measure of how hot or cold something is.

Temperature Scales Kelvin Celsius Fahrenheit Boiling Point (H2O) 373 100 212 Melting Point (H2O) 273 32 Absolute Zero -273 -459

Consider the way pressure changes with temperature in a gas: Gay-Lussac’s Law P α T Pressure Temperature Gas 1 Gas 2 Pressure must always be greater than zero So temperature can never go below this point: T = -273.15 ° C = Absolute Zero

Determine Absolute Zero using Vernier Pressure sensor Temperature and pressure demo.pptx –U-tube manometer

Pressure Law Use Vernier and extrapolate temperature until P = 0 ie T should = -273C

A new temperature unit: Kelvins (K) 0 K = absolute zero = -273.15 ° C Kelvins are the same size as Celsius degrees Kelvins are the SI unit for temperature To convert: TC = Celsius temp. T = Kelvin temp. T = TC + 273.15

Thermal Expansion When the washer is heated The hole becomes larger

Some consequences of Linear Expansion: Concrete buildings expand Bridges need expansion joints Dental fillings must expand at the same rate as teeth

Recall: Most materials expand if heated Exception: Water contracts from 0°C 4°C This is the most dense water gets (in any state) Consequence: In the winter, lakes freeze from the top down

Which is most likely liquid water? discussion how do you know? A I am not sure that my students remember that water is less dense in solid form, but this would be a good time to remind them that ice floats. A B C

Thermal Expansion DL Lo DL  LoDT DT DL = aLoDT L - Lo = aLoDT Coefficient of linear expansion L = Lo(1+aDT)

Thermal Expansion Expansion Problem sleeve shaft D d A cylindrical brass sleeve is to be shrunk-fitted over a brass shaft whose diameter is 3.212 cm at 0 oC. The diameter of the sleeve is 3.196 cm at 0 oC. To what temperature must the sleeve be heated before it will slip over the shaft?

Thermal Expansion shaft sleeve Expansion Problem D d Expansion Problem To what temperature must the sleeve be heated before it will slip over the shaft?

Thermal Expansion Volume Expansion New Volume Lo Lo + DL Initial Volume DL = aLoDT

Thermal Expansion Coefficient of Volume Expansion

Thermal Expansion Expansion Problem An automobile fuel tank is filled to the brim with 45 L of gasoline at 10 oC. Immediately afterward, the vehicle is parked in the Sun, where the temperature is 35 oC. How much gasoline overflows from the tank as a result of expansion? Change in volume of the steel gas tank Overflow Change in volume of the gasoline