Chapters 21-22 Physics

Question 1

WHAT ARE THE MACRO/MICRO PROPERTIES OF A SOLID?

Answer 1

it has a defined shape and a fiXed volume; there are strong forces of attraction and a short separation between the particles

Question 2

WHAT ARE THE MACRO/MICRO PROPERTIES OF A LIQUID?

Answer 2

it has a fixed volume but not a defined shape; the particles are close together (but less than in a solid) and the forces of attraction are weaker than in a solid

Question 3

WHAT ARE THE MACRO/MICRO PROPERTIES OF A GAS?

Answer 3

it has no fixed volume nor defined shape; the particles are far away from each other and there are no forces of attraction

Question 4

WHY DO WE NEED MORE ENERGY TO CONVERT A SOLID INTO A GAS THAN TO CONVERT A SOLID INTO A LIQUID?

Answer 4

because the bonds between the particles are being broken, not just weakened

Question 5

DEFINE ‘LATENT HEAT’

Answer 5

the latent heat is the energy required per unit mass of a substance to raise the temperature

Question 6

STATE THE ZEROTH LAW OF THERMODYNAMIC

Answer 6

if object A is in thermal equilibrium with object B, and object B is in thermal equilibrium with object C, then object A must be in thermal equilibrium with object C

Question 7

STATE A FEW METHODS OF HEAT TRANSFER

Answer 7

conduction (works with all materials), convection (the flow of heated particles in a fluid), radiations (works with no material)

Question 8

STATE THE FIRST LAW OF THERMODYNAMIC

Answer 8

energy is always conserved

Question 9

WHAT’S AN ISOBARIC PROCESS?

Answer 9

it’s when the pressure remains constant

Question 10

WHAT’S AN ADIABATIC PROCESS?

Answer 10

it’s when no energy leaves or enters the system as heat

Question 11

WHAT’S AN IDEAL GAS?

Answer 11

it’s a perfect model of a gas; it doesn’t really exist but we can get an accurate prediction of what it does

Question 12

WHAT’S MEANT BY BROWNIAN MOTION?

Answer 12

the brownian motion is the erratic motion of the particles, and it provides evidence of the fast and random movement of molecules in a gas

Question 13

WHAT’S THE ABSOLUTE ZERO?

Answer 13

it’s when the particles have no kinetik/vibrational energy (-273°C) but it doesn’t exist in nature

Question 14

WHAT’S TEMPERATURE?

Answer 14

temperature is the measure of the kinetik/vibrational energy of the particles

Question 15

WHAT’S PRESSURE?

Answer 15

pressure is the result of the collisions of the air molecules with the walls of a box, with your body etc.

Question 16

WHAT’S THE VOLUME?

Answer 16

the volume is the space occupied

Question 17

STATE BOYLE’S LAW

Answer 17

at constant temperature, the pressure is inversely proportional to the volume (p1 x v1 = p2 x v2)

Question 18

STATE CHARLES’ LAW

Answer 18

at constant pressure, temperature is directly proportional to the volume (T1 : v1 = T2 : v2)

Question 19

STATE GAY LUSSAC’S LAW

Answer 19

at constant volume, pressure is directly proportional to temperature

Question 20

WHAT’S A HEAT ENGINE?

Answer 20

a heat engine is a device that takes in energy as heat and partially converts it into work

Question 21

WHAT’S A HEAT PUMP?

Answer 21

a heat pump is a device that pumps heat from cold to hot

Question 22

STATE THE SECOND LAW OF THERMODYNAMIC

Answer 22

no heat engine operating in a cycle can absorb energy from a reservoir and use it entirely for the performance of an equivalent amount of work (=nothing is 100% efficient)

Question 23

DEFINE ENTROPY

Answer 23

entropy is the measure of chaos and disorder, which increases in all natural processes. if the laws of nature are allowed to act without interference a disorderly arrangement is much more probable than an orderly one

Question 24

STATE THE THIRD LAW OF THERMODYNAMIC

Answer 24

it’s impossible for any process, no matter how idealised, to reduce the entropy of a system to its absolute-zero value in a finite number of operations

Question 25

WHAT’S THE INTERNAL ENERGY OF AN OBJECT?

Answer 25

the internal energy of an object is the sum of its kinetik and potential energy