Physical Quantities and SI units

Question 1

What is a Physical quantity?

Answer 1

The physical quantity is the arithmetical product of a numerical value and a unit:
Physical quantity = numerical value · unit.
It is characterized by a letter for example m=mass.

Question 2

What is a Scalar?

Answer 2

A physical quantity that has a magnitude describable by a real number and NO DIRECTION . e.g., body temperature. The expression T = 37 °C fully describes the quantity.

Question 3

What is a Vector?

Answer 3

A physical quantity with spatial direction, e.g. the speed of an aircraft. To fully describe the quantity it is not enough to give the magnitude and unit of speed (e.g. 900 km/h), but the DIRECTION of movement must also be provided.

Question 4

SI Base Units

What is the SI Unit for Time? Symbol?

Answer 4

Time - Seconds - s

Question 5

SI Base Units

What is the SI Unit for Length? Symbol?

Answer 5

Length - Meters - m

Question 6

SI Base Units

What is the SI Unit for Mass? Symbol?

Answer 6

Mass - Kilograms - kg

Question 7

SI Base Units

What is the SI Unit for Electric current? Symbol?

Answer 7

Electric current - Ampere - A

Question 8

SI Base Units

What is the SI Unit for Temperature? Symbol?

Answer 8

Temperature - Kelvin - K

Question 9

SI Base Units

What is the SI Unit for Amount of Substance? Symbol?

Answer 9

Amount of Substance - mole - mol

Question 10

SI Base Units

What is the SI Unit for Unit of Luminous Intensity?Symbol?

Answer 10

Luminous Intensity - candela - cd

Question 11

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^15? Symbol?

Answer 11

peta = 10^15, Symbol is P

e.g. 2 petameter = 2 x 10^15 meter = 2 Pm

Question 12

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^12? Symbol?

Answer 12

tera = 10^12, Symbol is T

e.g. 2 terameter = 2 x 10^12 meter = 2 Tm

Question 13

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^9? Symbol?

Answer 13

giga= 10^9, Symbol is G

e.g. 2 gigameter = 2 x 10^9 meter = 2 Gm

Question 14

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^6?Symbol?

Answer 14

mega= 10^6, Symbol is M

e.g. 2 megameter = 2 x 10^6 meter = 2 Mm

Question 15

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^3? Symbol?

Answer 15

kilo= 10^3, Symbol is k

e.g. 2 kilometer = 2 x 10^3 meter = 2 km

Question 16

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^2? Symbol?

Answer 16

hecto= 10^2, Symbol is h

e.g. 2 hectometer = 2 x 10^2 meter = 2 hm

Question 17

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^1? Symbol?

Answer 17

deca= 10^1, Symbol is da

e.g. 2 decameter = 2 x 10^1 meter = 2 dam

Question 18

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-1? Symbol?

Answer 18

dec= 10^-1, Symbol is d

e.g. 2 decimeter = 2 x 10^-1 meter = 2 dm

Question 19

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-2? Symbol?

Answer 19

centi= 10^-2, Symbol is c

e.g. 2 centimeter = 2 x 10^-2 meter = 2 cm

Question 20

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-3? Symbol?

Answer 20

milli= 10^-3, Symbol is m

e.g. 2 millimeter = 2 x 10^-3 meter = 2 mm

Question 21

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-6? Symbol?

Answer 21

micro= 10^-6, Symbol is μ

e.g. 2 micrometer = 2 x 10^-6 meter = 2 μm

Question 22

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-9? Symbol?

Answer 22

nano= 10^-9, Symbol is n

e.g. 2 nanometer = 2 x 10^-9 meter = 2 nm

Question 23

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-12? Symbol?

Answer 23

pico= 10^-12, Symbol is p

e.g. 2 picometer = 2 x 10^-12 meter = 2 pm

Question 24

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-15? Symbol?

Answer 24

femto= 10^-15, Symbol is f

e.g. 2 femtometer = 2 x 10^-15 meter = 2 fm

Question 25

Prefixes for the International System of Units (SI) Powers of ten Prefix for 10^-18? Symbol?

Answer 25

atto= 10^-18, Symbol is a | e.g. 2 attometer = 2 x 10^-18 meter = 2 am

Question 26

Distance (m) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 26

Distance (m) is a Scalar Magnitude without Direction e.g. The distance between the moon and the earth

Question 27

Displacement (m) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 27

Displacement (m) is a Vector Magnitude with a Direction e.g. The displacement path of someone on earth to the moon.

Question 28

Speed (m/s) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 28

Speed (m/s) is a Scalar Magnitude without Direction e.g. the speed of a box on a moving straight assembly line

Question 29

Velocity (m/s) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 29

Velocity (m/s) is a Vector Magnitude with a Direction e.g. the velocity of a rat running perpendicular to the moving assembly line

Question 30

Time (s) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 30

Time (s) is a Scalar Magnitude without Direction e.g. the time necessary to boil an egg in room temperature

Question 31

Mass (kg) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 31

Mass (kg) is a Scalar Magnitude without Direction e.g. the mass of an egg

Question 32

Weight (N) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 32

Weight (N) is a Vector Magnitude with a Direction e.g. the weight of a egg pressing against you as you try to lift it up.

Question 33

Acceleration (m/s^2) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 33

Acceleration (m/s^2) is a Vector Magnitude with a Direction e.g. The deceleration of your car as you hit the brake to reach a full stop (*against the vector of you velocity).

Question 34

Temperature (K)- Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 34

Temperature (K) is a Scalar Magnitude without Direction e.g. the temperature of a boiled egg

Question 35

Pressure (Pa)- Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 35

Pressure (Pa) is a Scalar Magnitude without Direction e.g. the pressure at the depth of 20 meters below sea level

Question 36

Force (N)- Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 36

Force (N) is a Vector Magnitude with a Direction e.g. The Force that you apply against an egg's weight in order to lift it up.

Question 37

Work (J) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 37

Work (J) is a Scalar Magnitude without Direction e.g. the Work done by you lifting an egg from the table to the pot or the work done by you lifting an egg from the pot to the table

Question 38

Power (J/s) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 38

Power (J/s) is a Scalar Magnitude without Direction e.g. the Work done by you lifting an egg from the table to the pot PER SECOND

Question 39

Moment (N*m) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 39

Moment (N*m) is a Vector Magnitude with a Direction e.g. The Moment of an egg as it hits the wall when you throw it in a specific angle and force

Question 40

Energy (J) - Scalar or Vector? | ** This term will be fully explained as we move to the next sections of the course

Answer 40

Energy (J) is a Scalar Magnitude without Direction e.g. the Energy needed (Heat) in order to boil an egg

Question 41

Greek Alphabet - Used in Sciences What is this letter - α ? What is the use of this letter in Physics?

Answer 41

α - Alpha | It is used to denote Multiple Quantities: Angle, Alpha type of Radiation and Angular Acceleration.

Question 42

Greek Alphabet - Used in Sciences What is this letter - β ? What is the use of this letter in Physics?

Answer 42

β- Beta | It is used to denote Multiple Quantities: Angle and Beta type of Radiation.

Question 43

Greek Alphabet - Used in Sciences What is this letter - γ ? What is the use of this letter in Physics?

Answer 43

γ - Gamma | It is used to denote Multiple Quantities: Gamma type of Radiation and therefore it is also the symbol for a Photon.

Question 44

Greek Alphabet - Used in Sciences What is this letter - δ? What is the use of this letter in Physics?

Answer 44

δ - Delta | It is used to denote Multiple Quantities of them Angle is the one relevant for us.

Question 45

Greek Alphabet - Used in Sciences What is this letter - Δ? What is the use of this letter in Physics?

Answer 45

Δ - Uppercase Delta It is used to denote a CHANGE in a physical quantity. For example, the change of Time is denoted as Δt.

Question 46

Greek Alphabet - Used in Sciences What is this letter - ε? What is the use of this letter in Physics?

Answer 46

ε - Epsilon | It is used to denote the Dielectric Constant of a Substance or Relative permittivity.

Question 47

Greek Alphabet - Used in Sciences What is this letter - θ? What is the use of this letter in Physics?

Answer 47

θ - Theta | It is used to denote Multiple Quantities of them Angle is the one relevant for us.

Question 48

Greek Alphabet - Used in Sciences What is this letter - κ? What is the use of this letter in Physics?

Answer 48

κ - Kappa | It is used to denote Multiple Quantities of them Diffusion Constant is the one relevant for us.

Question 49

Greek Alphabet - Used in Sciences What is this letter - λ? What is the use of this letter in Physics?

Answer 49

λ - Lambda | It is used to denote Multiple Quantities: Wave Length, Volume and Radioactive Decay.

Question 50

Greek Alphabet - Used in Sciences What is this letter - μ? What is the use of this letter in Physics?

Answer 50

μ - Miu | It is used to denote Multiple Quantities: Micro- (10^-6) and Friction Constant.

Question 51

Greek Alphabet - Used in Sciences What is this letter - π? What is the use of this letter in Physics?

Answer 51

π - Pi It is used to denote the Constant Geometric Ratio between the Circumference of a circle to its Diameter. π = 3.1416 (Always).

Question 52

Greek Alphabet - Used in Sciences What is this letter - ρ? What is the use of this letter in Physics?

Answer 52

ρ - Rho | It is used to denote Multiple Quantities: Density, Charge Density and Specific Electrical Resistance.

Question 53

Greek Alphabet - Used in Sciences What is this letter - Σ? What is the use of this letter in Physics?

Answer 53

Σ - Uppercase Sigma | It is used to denote SUMMATION in Mathematics and Physics. ΣF = F1 + F2 + F3.

Question 54

Greek Alphabet - Used in Sciences What is this letter - σ? What is the use of this letter in Physics?

Answer 54

σ - Sigma | It is used to denote Charge Density over Area.

Question 55

Greek Alphabet - Used in Sciences What is this letter - ω? What is the use of this letter in Physics?

Answer 55

ω - Omega | It is used to denote Angular Frequency and Angular Velocity.

Question 56

Greek Alphabet - Used in Sciences What is this letter - Ω? What is the use of this letter in Physics?

Answer 56

Ω - Uppercase Omega | It is used to denote the Unit Ohm for Electrical Resistance.

Question 57

Greek Alphabet - Used in Sciences What is this letter - ψ? What is the use of this letter in Physics?

Answer 57

ψ - Psi | It is used to denote the Electric Flux.

Question 58

Greek Alphabet - Used in Sciences | What is this letter - Φ?

Answer 58

Φ - Phi | It is used to denote the Electric Potential.

Question 59

Greek Alphabet - Used in Sciences What is this letter - τ? What is the use of this letter in Physics?

Answer 59

τ - Tau | It is used to denote the Time of Charging in RC Circuits.

Question 60

Greek Alphabet - Used in Sciences What is this letter - ν? What is the use of this letter in Physics?

Answer 60

ν - Nu | It is used to denote the Frequency (as alternative for f).

Question 61

What are the Base Quantities ?

Answer 61

Chosen quantities, all other quantities are originated from them. These are : Time, Length, Mass, Electric Current, Temperature, Amount of Substance and Luminous Intensity.

Question 62

What are Derived quantities and their units?

Answer 62

Derived quantities and their units are defined by using the base quantities and base units.They are usually defined by a formula.

Question 63

Give an example for a derived quantity and it's unit using Length with Time. Add the Formula.

Answer 63

Velocity (𝑣) is defined as the distance (or length) travelled (Δx) in an interval of time (Δ𝑡) divided by the duration of that interval (𝑣 = Δx/Δ𝑡). It's unit is[m/s^2] . ** You will get more familiar with the Derived quantities and units as we advance in our Biophysics course.

Question 64

Give an example for a derived quantity and it's unit using 2 different Lengths (2 Dimensional Value). Add the Formula.

Answer 64

Area (A) is defined as the length (x1) of an interval times another length (x2) of an interval (A = x1*x2). It's unit is [m^2] . ** You will get more familiar with the Derived quantities and units as we advance in our Biophysics course.

Question 65

Give an example for a derived quantity and it's unit using 3 different Lengths (3 Dimensional Value). Add the Formula.

Answer 65

Volume (V) is defined as the length (x1) of an interval times another length (x2) of an interval and times another length (x3) of an interval (A = x1*x2*x3). It's unit is [m^3] . ** You will get more familiar with the Derived quantities and units as we advance in our Biophysics course.