12PHB - Term 2 (D1 C1 C2 B4)

Question 1

Newton’s Law of Gravitation equation

Answer 1

F = G (Mm)/r^2

Question 2

Inverse square law

Answer 2

F ∝ 1/r^2
When a mass is twice as far away from another, the force by gravity reduces by 1/4

Question 3

gravity force and centripetal force

Answer 3

They are equal (Fg = Fc)

Question 4

Define Gravitational field

Answer 4

A region of space where a test mass experiences a force due to the gravitational attraction of another mass

Question 5

Define Weight force

Answer 5

The force due to gravity

Question 6

Equation for density

Answer 6

D = m/V

Question 7

Define a point mass

Answer 7

A body covers a very large distance compared to its size, so, to study its motion, its size or dimension can be neglected

Question 8

Kepler’s First Law

Answer 8

The orbit of a planet is an ellipse, with the Sun at one of the two foci

Question 9

Kepler’s Second Law

Answer 9

A line segment joining the Sun to a planet sweeps out equal areas in equal time intervals.

Question 10

Kepler’s Third Law

Answer 10

For planets or satellites in a circular orbit about the same central body, the square of the time period is proportional to the cube of the radius of the orbit (T^2 ∝ r^3)

Question 11

Kepler’s Third Law equation

Answer 11

T^2 = 4π^2 r^3 / GM

Question 12

T^2 ∝ r^3 Graph

Answer 12

2 log T ∝ 3 log r will give a linear graph (3 log r on x-axis)

Question 13

Change in internal energy and temperature

Answer 13

ΔU ∝ ΔT

Question 14

When a gas expands…

Answer 14

Work is done on its surroundings by exerting pressure on the walls of the container it is in

Question 15

Compression/Expansion on work

Answer 15

Compressed (-V) = -W
Expansion (+V) = +W

Question 16

Pressure-Volume Graph

Answer 16

Volume on the x-axis and Pressure on the y-axis

Question 17

When both pressure and volume change

Answer 17

Work done can be determined from the area under the p-v gaph

Question 18

First law of Thermodynamics

Answer 18

Based on the principle of conservation of energy. Q = ΔU + W

Question 19

Define Entropy

Answer 19

A measure of how disordered a system is

Question 20

How can entropy increase

Answer 20

• Phase change (s - l - g)
• Dissolving a solid in a solvent
• Gas diffusing

Question 21

Define Reversible process

Answer 21

A process where there is no overall change in entropy as the system and its surroundings are returned to there original states

Question 22

Define Irreversible process

Answer 22

A process which results in an increase in entropy as the system and its surroundings cannot return to their original states

Question 23

Define Isolated system

Answer 23

A system where neither matter nor energy can be transferred in or out

Question 24

Entropy equation

Answer 24

ΔS = ΔQ/T

Question 25

Define Microstate

Answer 25

One state or possible arrangements of the particles in the system

Question 26

Find Ω

Answer 26

Ω = (num of compartments)^(num of particles)

Question 27

Second law of Thermodynamics

Answer 27

In every process, the total entropy of an isolated system always increases

Question 28

Clausius form of the second law of thermodynamics

Answer 28

Thermal energy cannot spontaneously transfer from a region of lower temperature to a region of higher temperature

Question 29

Kelvin form of the second law of thermodynamics

Answer 29

When extracting energy from a heat reservoir, it is impossible to convert it all into work

Question 30

The four thermodynamics processes

Answer 30

- Isobaric (Constant pressure) - Isovolumetric (Constant volume) - Isothermal (Constant temperature/ΔU) - Adiabatic (Constant Q)

Question 31

Isobaric

Answer 31

A process in which no change in pressure occurs (V/T = constant)

Question 32

Isovolumetric

Answer 32

A process where no change in volume occurs and the system does no work (Q = ΔU)

Question 33

Isothermal

Answer 33

A process in which no change in temperature occurs (Q = W) (Follow the isotherms on the graph)

Question 34

Adiabatic

Answer 34

A process where no heat is transferred into or out of the system (-W = ΔU)

Question 35

Adiabatic process equation

Answer 35

pV^5/3 = constant

Question 36

Heat engines

Answer 36

Converts thermal energy into mechanical work

Question 37

Heat engine operation

Answer 37

- Work done by gas (expansion) - Heat extracted - Work done on gas (compression) - Heat added

Question 38

efficeincy of heat engines

Answer 38

n = 1 - Qc/Qh

Question 39

The carnot cycle

Answer 39

The thermodynamic system that runs at its greatest possible efficiency

Question 40

The carnot cycle operation

Answer 40

- Isothermal expansion - Adiabatic expansion - Isothermal compression - Adiabatic compression

Question 41

Define oscillation

Answer 41

The repetitive variation with time of the displacement of an object about the equilibrium position

Question 42

Define equilibrium position

Answer 42

The position when there is no resultant force acting on an object (fixed central point object oscillated around)

Question 43

Define Displacement

Answer 43

The horizontal or vertical distance of a point on the wave from its equilibrium position

Question 44

Define Period

Answer 44

The time interval for one complete oscillation measured in seconds

Question 45

Define isochronous

Answer 45

Oscillations that have a constant period

Question 46

Define amplitude

Answer 46

The maximum value of displacement on either side of the equilibrium position

Question 47

Define frequency

Answer 47

The number of oscillations per second measured in hertz

Question 48

Define angular frequency

Answer 48

The rate of change of angular displacement with respect to time (rad s-1)

Question 49

Relationship between frequency and period

Answer 49

f = 1/T

Question 50

Conditions for simple harmonic motion

Answer 50

- Acceleration is proportional to the horizontal or vertical displacement - Acceleration is in the opposite direction to the displacement

Question 51

Qualities of simple harmonic motion oscillations

Answer 51

- max horizontal and vertical displacement on either side of the equilibrium position are equal - time period for each vibration is constant - the restoring force is horizontally or vertically towards the equilibrium position, proportional to the distance from it

Question 52

What does the equation a = -w^2 x demonstrate

Answer 52

Acceleration reaches its maximum value when the displacement is at a maximum

Question 53

acceleration and velocity in relation to amplitude

Answer 53

-A => a = max & v = 0 0 => a = 0 & v = max A => a = max & v = 0

Question 54

Natural frequency

Answer 54

Frequency at which an object vibrates or oscillates naturally when disturbed from its equilibrium

Question 55

Total energy in a SHM system

Answer 55

E = Ep + Ek

Question 56

When to use PV^5/3 = constant

Answer 56

In a adiabatic process

Question 57

Qualities of the Carnot cycle

Answer 57

- Slow process - not realistic because it is so slow - Most efficient cyclic process we know