Cambridge IGCSE Physics (Theory Workbook, Carol Tear) · Exercise 4E exam-style, pp.30–31
Physics — Ch.4 Forces (Ex 4E, pp.30–31)
Graded 2026-06-18 · Sys4Ethan (Claude Opus 4.8 vision, human-verified)
Qp30 · Q1 (spring graph)
✓ Correct
load–extension graph
(a) extension $28\div2.5 = 11.2$ cm; (b) weight $5\,\text{cm}\times2.5 = 12.5$ N; (c) spring constant $2.5$ N/cm — all correct, working shown.
Qp30 · Q2 (drone forces)
✓ Correct
resultant force + a=F/m
(a) $20-12-5 = 3$ N upward; (b) $0.75\div2.5 = 0.3$ m/s² ✓.
Qp31 · Q3 (turning effect)
✓ Correct
moments comparison
Object C — $3\,\text{N}\times3\,\text{m}=9$ N·m, the largest moment ✓.
Qp31 · Q4 (circular motion)
✓ Correct
centripetal force
(b) right: same mass & speed, the smaller radius needs the larger centripetal force, so the force on A > B. (a) arrow toward the centre.
Qp31 · Q5 (stability)
✓ Correct
stability
Position A — largest base area + lowest centre of gravity ✓.
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