Definitions

Question 1

Absolute humidity

Answer 1

Mass of water vapour present in a sample of air at a given temperature (kgm-3)

Question 2

Absolute zero

Answer 2

Lowest possible temp. where nothing could be colder and all thermal motion stops (0k)

Question 3

Boiling point

Answer 3

temperature at which vapour pressure equals the surrounding ambient pressure and changes into a vapour.

Question 4

SI units

Answer 4

SMMACKK

Seconds
Moles
metre
ampere
candela
kelvin
kilogram

Question 5

Second

Answer 5

The duration of a certain number of oscillations of a
caesium-133 atom

Question 6

Mole

Answer 6

The amount of substance that contains the same number of
particles as there are atoms in 0.012 kg (12 g) of carbon-12

Question 7

Metre

Answer 7

Length travelled by light in a vacuum in 1/300 000 000 of a
second

Question 8

Ampere

Answer 8

The current in two parallel conductors of infinite length,
placed 1 metre apart in a vacuum that would produce
force of 2x10-7 N/m

OR
1 coulomb per second

Question 9

Candela (cd)

Answer 9

Luminous intensity of monochromatic light

Question 10

Kelvin

Answer 10

1/273.16 of the thermodynamic triple point of water

Question 11

Kg

Answer 11

The mass of the prototype kilogram held in Sèvres, France, changed in 2019 to be defined by the planck constnat

Question 12

Newton

Answer 12

Derived SI unit of force. THe force required to accelerate one kg by 1m/s^2

Question 13

Pressure

Answer 13

Is force/unit area
DErived SI unit is the pascal (Pa)

Question 14

Pascal

Answer 14

Derived SI unit of pressure
1Pa is one newton over one m^2

Question 15

Joule

Answer 15

Derived SI unit of energy
1 joule is the work done when applying a force of one newton through a distance of 1m
Units are therefore Nm

Question 16

Volt

Answer 16

Derived SI unit of electrical potential
1 volt is the potential difference between two points of a conducting wire where 1 joule of work is done to move 1 coulomb of charge between them
OR
PD between two points of wire when 1 amp dissipates 1 watt of power between them
OR
1 volt will ‘push’ 1 amp of current through a resistance of 1 ohm

Question 17

Watt

Answer 17

Derived unit of power
1 watt = 1J/S

Question 18

Ohm

Answer 18

Derived unit of electrical resistance
Resistance between two points of a conductor when a constant PD of one volt produces a current of 1 amp

Question 19

Hertz

Answer 19

Derived SI unit of frequency
1 hz is one cycle per second

Question 20

Coulomb

Answer 20

Is the unit of charge
1C is the amount of charge passing a given point / second, when 1A of current is flowing
1C=1A x 1s
OR the magnitude of charge possessed by 6.24 x 10^18 electrons

Question 21

Kinetic energy

Answer 21

The energy a body possesses because of its motion
The energy needed to accelerate the object from a state of rest to its given velocity. Also equal to the work it would do when decelerating to return to rest.

Question 22

Potential energy

Answer 22

The enerdy of a body or system as a result of its position in an electric, magnetic or gravitational field. The potential of that body to do work.

Question 23

Force

Answer 23

That which changes a body’s state of rest or motion.
Derived SI unit is a newton
1N is required to accelerate 1KG by 1m/s^2
Force has both magnitude and direction. making it a vector
F=MXA

Question 24

Momentum

Answer 24

= mass x velocity.

Question 25

pH

Answer 25

negative log base 10 of hydrogen ion concentrationt

Question 26

Critical temp

Answer 26

Temperature above which a gas cannot be liquefied, regardless of the pressure applied

Question 27

Critical pressure

Answer 27

The pressure required to liquefy a gas at its critical temperature

Question 28

Filling ration

Answer 28

mass of a cylinder filled with N2O compared to the mass of water that cylinder would hold. 0/75 or 0.67 in ho t places