Strong Nuclear Force

• What is the strong nuclear force?

  An attractive force between nucleons

  
• Why is gravity considered negligible in the nucleus?

  It is the weakest of the fundamental forces
• What would happen if only electrostatic forces acted in the nucleus?

  The nucleus would not hold together
• What particles does the strong nuclear force act between?

  Quarks
• How do protons and neutrons relate to quarks?

  They are made up of quarks
• What role does the strong nuclear force play in the nucleus?

  It holds the nucleus together

  
• What are the properties of the strong nuclear force?

  • Varies with separation between nucleons
  • Repulsive below 0.5 fm
  • Attractive up to 3.0 fm
  • Maximum attraction at around 1.0 fm
  • Equilibrium at about 0.5 fm
  • Small range: 0.5 to 3.0 fm

  
• At what separation is the strong nuclear force repulsive?

  Below 0.5 fm

  
• At what separation does the strong nuclear force become attractive?

  Up to 3.0 fm
• What is the maximum attractive value of the strong nuclear force?

  Occurs at around 1.0 fm
• What is the equilibrium position for nucleons?

  About 0.5 fm separation
• How does the range of the strong nuclear force compare to other fundamental forces?

  It has a very small range
• How do the electrostatic and strong forces compare in terms of strength and range?

  • Strong force is stronger between 0.5 and 3.0 fm
  • Electrostatic force has a larger range
  • Electrostatic force is significant over 2.5 fm
  • Strong force is not influenced by charge
• What does the red curve in the graph represent?

  The strong nuclear force between nucleons

  
• What does the blue curve in the graph represent?

  The electrostatic repulsion between protons

  
• What happens to the strong force after 3.0 fm?

  It becomes zero
• What is the value of 1 femtometre (fm) in meters?

  $1 \times 10^{-15} \text{ m}$
• What should you remember about the strong nuclear force for exams?

  • Also known as the strong interaction
  • Key values: range = 0.5 to 3.0 fm
  • Typical nuclear separation ≈ 1.0 fm
  • Strong force becomes zero after 3 fm