Work and Energy Topic Review summary

Key learning points

• Work by a constant force: $W=Fd\\cos\\alpha$.
• KE $=\\frac12 mv^2$; gravitational PE $=mgh$ (near Earth).
• Work–energy: work by all forces = change in KE (or use mechanical energy + work by non-conservative forces).
• Power $=Fv$ for a driving force in the direction of motion.
• Conservation of mechanical energy when only conservative forces do work.

Worked example 1 — KE gain

Mass 2 kg, 3→5 m/s. ΔKE?

Working

$\\frac12 m(v^2-u^2)$.

Worked example 2 — Power

Driving force 200 N at 15 m/s. Power?

Working

$P=Fv$.

Worked example 3 — Work by a constant force: W=Fd\\\\cos\\\\a

Work by a constant force: $W=Fd\\\\cos\\\\alpha$.

Working

Attempt without notes, then check the answers PDF.

Worked example 4 — KE =\\\\frac12 mv^2; gravitational PE =mgh

KE $=\\\\frac12 mv^2$; gravitational PE $=mgh$ (near Earth).

Working

Attempt without notes, then check the answers PDF.

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.