A-level · Forces & Newton's laws

Statics — equilibrium under several forcesExam-style questions

A particle in equilibrium has zero resultant, so resolving in two perpendicular directions gives two equations — used to find unknown forces or angles, including on rough slopes where friction is at its limit (F = μR) on the point of moving.

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17 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 3 Level 4 Level 5

1
A particle of mass $5$ kg rests on a rough slope of $30^\circ$ with coefficient of friction $0.4$ . A force $P$ acts up the slope.
(a) Find the least value of $P$ that keeps the particle from sliding down.
(b) Find the greatest value of $P$ before it slides up. Give answers to 3 s.f. ( $g = 9.8$ .)
Level 5 · 4 marksTry it
2
A particle of mass $4$ kg rests on a rough plane inclined at $30^{\circ}$ to the horizontal, with coefficient of friction $0.25$ . A force $P$ acts up the slope, and the particle is on the point of sliding down the slope.

Find $P$ , giving your answer to 3 significant figures. (5 marks)
Level 5 · 5 marksTry it