Thermometers
This is the S.I unit of temperature
Degrees celsius
or Kelvin
This experiment can be used to observe expansion.
1. Bar breaker experiment
or
2. Bar and gauge experiment
This device is used to measure temperature.
A thermometer
This is used to measure the pressure of a gas
Bourdon gauge
(Accept Barometer)
What does "delta theta" refer to in the heat equation
Change in temperature or T2--T1
This is the name of the type of thermometer used in schools by students
Liquid in glass bulb thermometer
What happens to substances are they are heated or cooled?
They expand on heating and contract on cooling.
(except water)
This determines the flow of heat
Temperature
What is the general gas law
P1V1/T1 = P2V2/T2
State the heat equation
E = m c (T2-T1)
These are two features of a clinical thermometer
1. Narrow constriction just beyond the bulb
2. A range of temperature above/below the avg. temperature (35- 42 oC)
List 2 problems associated with thermal expansion
1. Cracking of glass vessels
2. Busting of pipes
3. Danger to telephone wires/power lines
Brownian motion is....
the phenomenon whereby smoke particles collide with air particles , seen by bright specks of light - when viewed under a microscope.
State Boyle's law
The volume of a fixed mass of gas is inversely proportional to the pressure provided the temperature is constant.
Define the term specific heat capacity of a substance
This is the quantity of heat required to increase the temperature of a substance in unit mass.
The upper fixed point and lower fixed point are defined as.....
State these temperatures.
Upper Fixed point - the temperature of steam above pure boiling water. 100 oC
Lower fixed point - the temperature of pure melting ice.0oC
This precaution is taken when putting up power lines
Power lines (& over head cables) are put up with a sag in HOT weather, to allow for contraction at Nights when it is cooler.
State 3 features of a solid in terms of the kinetic theory of matter
Solids have a definite shape
Molecules of solids only have vibrational movement.
Solids are difficult to compress.
Solids are made of up regular, repeating structures (or units)
The force between the molecules are equal and opposite.
A gas of volume 2m3 @ 27oC is
(a) heated to 327oC
(b) cooled to -23 oC
What are the new volumes, V2
Change T1 = 27+273 = 300K
Use v1/T1= V2/T2
(a) T2 = 327+273 = 600K
V2 = 4 m3
(b) T2 = -23 +273 = 150K
V2 = 1m3
Give 3 differences between boiling and evaporation
1. Boiling has bubbles, evaporation no bubbles.
2 Boiling occurs at a definite temperature called the boiling point. Evaporation occurs at any temperature.
3. Boiling requires heat energy to be supplied.
4. Boiling has movement of the liquid itself, evaporation doesn't
5. Boiling occurs through out the liquid, evaporation occurs at the surface only.
Give 2 Advantages and 2 disadvantages of a thermocouple.
Advantages : Fast response, large range , can measure rapidly changing temperatures
Disadvantages - costly, training required
List 4 major keywords in relation to the kinetic theory
1. All matter consits of molecules
2. All molecules are in random motion always
3. The molecules move with a velocity
4. Force or momentum exerted when molecules collide
5. Molecules have various kinetic energies.
A bicycle pump contains 50 cm3 of air at 17oC and pressure 1atm. Find the pressure when the air is compressed to 10 cm3 and the temperature rises to 27oC
1. Change Temp to kelvin
2. Use the general gas law and rearrange for P2
Solution , P2 = 5.2 atm
A tank holding 60kg of water is heated by a 3kW electric heater for some time t. If the temperature rose from 10 oC to 60 oC and the specific heat capacity of water is 4200 J/ kgoC, find t.
Steps
Change 3KW to 3000 W
Apply the heat equation, rearraging to find t
Find delta theta = 50 oC
Ans = 4200 s