A LevelPhysicsAQAFlashcardsMeasurements & Their ErrorsUse of SI Units & Their Prefixes

Use of SI Units & Their Prefixes (AQA A Level Physics): Flashcards

Exam code: 7408

1/19

0Still learning

Know0

  • FrontSI Units

    Define SI base unit.

Cards in this collection (19)

  • Define SI base unit.

    An SI base unit is one of the seven fundamental units from which all other units in physics are derived.

  • Define derived unit.

    A derived unit is a unit obtained by combining SI base units according to a defining equation, such as the newton, joule or pascal.

  • Express the newton (N) in SI base units.

    Using force = mass × acceleration:

    \text{N} = \text{kg m s}^{-2}

  • Express the joule (J) and the pascal (Pa) in SI base units.

    Joule — from energy = ½mv²:

    \text{J} = \text{kg m}^{2}\text{ s}^{-2}

    Pascal — from pressure = force ÷ area:

    \text{Pa} = \text{kg m}^{-1}\text{ s}^{-2}

  • Name the six SI base units required for this course.

    • mass — kilogram (kg)

    • length — metre (m)

    • time — second (s)

    • electric current — ampere (A)

    • temperature — kelvin (K)

    • amount of substance — mole (mol)

  • True or False?

    The kilogram is an SI base unit.

    True.

    The kilogram (kg) is one of the seven SI base units.

  • State the prefix symbols and values for tera, giga, mega and kilo.

    • tera (T) = 1012

    • giga (G) = 109

    • mega (M) = 106

    • kilo (k) = 103

  • State the prefix symbols and values for centi, milli, micro, nano, pico and femto.

    • centi (c) = 10-2

    • milli (m) = 10-3

    • micro (μ) = 10-6

    • nano (n) = 10-9

    • pico (p) = 10-12

    • femto (f) = 10-15

  • How do you convert an energy from joules (J) to electronvolts (eV)?

    Divide the energy in joules by 1.6 × 10-19.

    To convert eV → J, multiply by 1.6 × 10-19.

  • What is 1 kilowatt-hour (kW h) in joules?

    1\text{ kW h} = 3.6 \times 10^{6}\text{ J} = 3.6\text{ MJ}

  • To convert an energy from joules to kilowatt-hours, .......... by 3.6 × 106.

    To convert an energy from joules to kilowatt-hours, divide by 3.6 × 106.

  • True or False?

    The prefix 'micro' represents a factor of 10-9.

    False.

    The prefix micro (μ) represents 10-6; the factor 10-9 is nano (n).

  • Define order of magnitude.

    The order of magnitude of a number is its value expressed to the nearest power of ten.

  • What is the order of magnitude of 6 × 108?

    109 — the value is rounded up because the coefficient 6 is greater than 5.

  • If one quantity is two orders of magnitude larger than another, how many times larger is it?

    100 times larger, i.e. a factor of 102.

  • A quantity that is one order of magnitude larger than another is about .......... times larger.

    A quantity that is one order of magnitude larger than another is about ten times larger.

  • Give the order of magnitude of the diameter of an atom and of a nucleus.

    • diameter of an atom ≈ 10-10 m

    • diameter of a nucleus ≈ 10-15 m

  • Estimate the mass of an adult person and the mass of a car.

    • mass of an adult person ≈ 70 kg

    • mass of a car ≈ 1000 kg

  • True or False?

    The order of magnitude of 3 × 108 is 109.

    False.

    The order of magnitude of 3 × 108 is 108; it rounds down because the coefficient 3 is less than 5.

Sign up to unlock flashcards
or

By signing up you agree to our Terms and Privacy Policy

Next:Limitation of Physical Measurements