Momentum and Impulse summary

Key learning points

• $\mathbf{J}=\Delta\mathbf{p}$ (and $\mathbf{J}=\mathbf{F}t$ for constant force).
• Conservation of momentum along a line for collisions/explosions without external impulse.
• Define a positive direction before writing equations.
• Units: kg·m/s for momentum; N·s for impulse.

Worked example 1 — Impulse

Mass $2\,\mathrm{kg}$ speeds from $3$ to $8\,\mathrm{m\,s^{-1}}$ same direction. Impulse?

Working

$J=m(v-u)=2\times5$.

Worked example 2 — (and for constant force)

Use this method from the Momentum and Impulse sheet: $\mathbf{J}=\Delta\mathbf{p}$ (and $\mathbf{J}=\mathbf{F}t$ for constant force).

Working

Each key learning point matches a question type on the printable worksheet.

Worked example 3 — Conservation of momentum along a line for collisions/ex

Use this method from the Momentum and Impulse sheet: Conservation of momentum along a line for collisions/explosions without external impulse.

Working

Each key learning point matches a question type on the printable worksheet.

Worked example 4 — Define a positive direction before writing equations

Use this method from the Momentum and Impulse sheet: Define a positive direction before writing equations.

Working

Each key learning point matches a question type on the printable worksheet.

Worked example 5 — Units: kg·m/s for momentum; N·s for impulse

Use this method from the Momentum and Impulse sheet: Units: kg·m/s for momentum; N·s for impulse.

Working

Each key learning point matches a question type on the printable worksheet.

Scaffolded Learning Sheet and answers (PDFs)

This page is a short, searchable overview for revision and search engines. Use the Scaffolded Learning Sheet first, then the Answers PDF for a full written solution. The printable PDFs remain the main classroom resource.