levo

The Nucleus and Radioactive Decay

The density of nuclear matter

  • 3 things to know
  • Unit A2 1

Overview

Value of the unified atomic mass unit and two assumptions made in estimating the density of nuclear matter.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

State the equation used to find the density of nuclear matter and define every symbol.

Key term

State the value of the unified atomic mass unit.

Numbers

Calculate the volume of an aluminium-27 nucleus, whose radius is 3.6 × 10⁻¹⁵ m.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the equation used to find the density of nuclear matter and define every symbol.

    Model answer

    ρ = m/V, where ρ is the density in kg m⁻³, m is the mass of the nucleus in kilograms and V is its volume in m³, taken as a sphere of radius R so that V = (4/3)πR³.

  2. 2

    How is the mass of a nucleus estimated from its nucleon number?

    Model answer

    The mass is taken as the nucleon number multiplied by the unified atomic mass unit, m = Au, where u = 1.66 × 10⁻²⁷ kg.

  3. 3

    State the value of the unified atomic mass unit.

    Model answer

    One unified atomic mass unit is 1.66 × 10⁻²⁷ kg.

  4. 4

    Calculate the volume of an aluminium-27 nucleus, whose radius is 3.6 × 10⁻¹⁵ m.

    Model answer

    V = (4/3)πR³ = (4/3)π × (3.6 × 10⁻¹⁵)³ = (4/3)π × 4.67 × 10⁻⁴⁴ = 1.95 × 10⁻⁴³ m³.

  5. 5

    Calculate the mass of an aluminium-27 nucleus in kilograms.

    Model answer

    m = Au = 27 × 1.66 × 10⁻²⁷ = 4.48 × 10⁻²⁶ kg.

  6. 6

    Estimate the density of nuclear matter using an aluminium-27 nucleus of mass 4.48 × 10⁻²⁶ kg and volume 1.95 × 10⁻⁴³ m³.

    Model answer

    ρ = m/V = 4.48 × 10⁻²⁶/(1.95 × 10⁻⁴³) = 2.3 × 10¹⁷ kg m⁻³.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The quarks and the .
leptonshadronsmesons

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AA current I is a charge q passing in time t.
BThe length l is vt.
CBIl becomes B × (q/t) × vt, which is Bqv.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Coulomb is a quantity of charge.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in The Nucleus and Radioactive Decay, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.