Lectures 1-7

Question 1

SI units

Answer 1

Used to standardise quantities used to measure physical properties including time, lengths, depth, mass, time, and energy. SI units help us communicate in a consistent universal way.

Question 2

Common SI units

Answer 2

Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature kelvin K
Amount of substance mole mol
Luminous intensity candela cd

Question 3

Derived quantities

Answer 3

combinations of SI units for example;
Speed = metre per second = m/s

Question 4

Prefixes

Answer 4

Extremely large or extremely small numbers

Question 5

Common prefixes

Answer 5

Giga G 10^9
Mega 10^6
Kilo 10^3
Centi 10^-2
Milli 10^-3
Micro 10^-6
Nano 10^-9

Question 6

Scientific notation

Answer 6

expressing number to the power of 10
for example;
1,000 = 1x10^3
3,000 = 3 x10^3
40,000 = 4 x 10^4

Question 7

Combining units with scientific notation

Answer 7

Every answer you give in physics needs units
The speed of light = 3.00 x 10^8 m/s

Question 8

Significant figure

Answer 8

indicate the precision of a number/measurement

Question 9

non-zero numbers

Answer 9

123 has 3 significant figures

Question 10

zeros between non-zero numbers

Answer 10

1002 has 4 significant figures

Question 11

leading zeros

Answer 11

0.00045 has 2 significant figures

Question 12

trailing zeros (if there’s a decimal place then yes if no decimal place then no)

Answer 12

50.0 has 3 significant figures
500 has 1 significant figure

Question 13

exact numbers

Answer 13

counted items such as “3 apples” has an infinite number of significant figures as it is not measured but counted

Question 14

why significant figures are important

Answer 14

more precise measurements
12m is less accurate than 12.00m

Question 15

Rule for multiplying/dividing

Answer 15

the answer should have the same amount of significant figures as the one with the SMALLEST significant figures.

3.2 x 4.56 =14.6

Question 16

Rule for adding/subtracting

Answer 16

The answer should have the same amount of decimal places as the one with the SMALLEST amount of decimal places.

12.34 + 0.6 =12.9

Question 17

uncertainties

Answer 17

every measurement has an uncertainty
usually expressed as +/-
shows the range of values within which the true values lie

5.6cm +/- 0.1cm means that the true value could be between 5.5cm or 5.7cm

Question 18

Temperature definition

Answer 18

a measure of the average kinetic energy of the particles in a substance.

related to the thermal energy of a substance

Question 19

Microscopic energy (molecular energy)

Answer 19

refers to the energy associated with the motion, arrangement and interactions of particles (atoms and molecules) that make up a substance.

Question 20

The several components of microscopic energy

Answer 20

Kinetic energy, energy due to the motion of its particles eg in gases particles move freely and have high kinetic energy (translational, vibrational, rotational)

potential energy, energy due to the position or arrangement of particles and the forces between them. eg in a liquid molecules are close but can move past each other, storing potential energy in their interactions (due to intermolecular forces)

internal energy, the total microscopic energy of a system, includes both the kinetic and potential energy of particles

Question 21

for an ideal gas, temperature

Answer 21

measures the average translational kinetic energy of the microscopic particles (atoms and molecules), which make up body

Question 22

ideal gas and energy equation

Answer 22

3/2 KbT = Ek_average = [1/2 mv^2] average

m = mass
T = temperature
Kb = Boltzmann constant
v = velocity
Ek = kinetic energy (energy of a moving body)

Question 23

Heat

Answer 23

the transfer of energy from a hotter body to a colder body in thermal contact until they are in thermal equilibrium

Question 24

Thermal equilibrium

Answer 24

two bodies that are at the same temperature

systems are said to be in equilibrium if they are able to transfer heat between each other but do not do so

Question 25

Thermometric property

Answer 25

-A property of a body which changes with temperature -required to measure temperature

Question 26

Celsius scale

Answer 26

Anders celsius (1701-1744) -put mercury in a vial -divided the distance between 2 points into 100 equal points -labelled each point as 1 degree each

Question 27

Calibration

Answer 27

a comparison between measurements, one of known magnitude or correctness made with the device to be calibrated

Question 28

Fahrenheit scale

Answer 28

Daniel Gabriel Fahrenheit (1724) used 3 points ice + water + aluminium chloride = 0 degrees ice + water = 32 degrees body temp = 96 degrees

Question 29

temperature in Fahrenheit from Celsius graph

Answer 29

Tf = 1.8Tc + 32

Question 30

T, V, P

Answer 30

Temperature is directly proportional to pressure if volume is constant. T goes up if P goes up if V is constant (P on y axis, T on x axis) Volume is inversely proportional to pressure if temperature is constant. V goes down if P goes up (1/P on y axis, V on x axis) ideal gas law, P = constant T/V (T/V on y axis, P on x axis)

Question 31

Ideal gas law

Answer 31

PV = nRT PV/T = constant P1V1/T1 = P2V2/T2

Question 32

Kelvin scale

Answer 32

Tk = Tc + 273

Question 33

Pressure

Answer 33

P = F/A P = pressure F = force A = Area

Question 34

Boyle's law

Answer 34

The pressure of a gas is inversely proportional to its volume at constant temperature and fixed quantity if a gas P1V1 = P2V2 PV = constant P = 1/V

Question 35

Charles law

Answer 35

The volume of a gas is directly proportional to its absolute temperature when the pressure and its number of moles remain constant V1/T1 = V2/T2 V/T = constant V directly proportional to T

Question 36

Universal gas constant

Answer 36

Slope = R = PV/nT

Question 37

Phases of materials

Answer 37

Solids (Closely packed, strongly bounded to neighbours, held rigidly in a fixed position) liquids (Still closely packed, Bonding is still quite strong, not held rigidly in a fixed position and bonds can break and reform) Gases (Widely spaced, only interact significantly on closest approach or collision)

Question 38

Specific heat capacity

Answer 38

The amount of energy required to change one unit of a substance by one degree Q = mc(delta)T

Question 39

Latent heat

Answer 39

The amount of heat energy required to change the phase f a substance without changing its temperature Q = ml

Question 40

Calorimetry

Answer 40

measuring the amount of heat energy transferred during a physical or chemical process. used to study the heat changes that occur during reactions, phase changes and temperature changes in substances.

Question 41

Method of mixtures

Answer 41

-based on the law of conservation of energy -when two substances of different temperatures are mixed together, the heat lost by the hot body is equal to the heat gained by the cold body -heat exchange occurs until the mixtures obtain equilibrium

Question 42

Conduction

Answer 42

The process by which heat or electricity is transferred through a substance or between substances in direct contact Q/T = KA(delta)T/L Q = energy T = Temp K = thermal conductivity of material A = cross-sectional area through which heat is transferred L = thickness of material

Question 43

Convection

Answer 43

heat transfer through the movement of a liquid

Question 44

radiation

Answer 44

the transfer of energy through electromagnetic waves