CAIE A-Level Mathematics 4.1.6 Limiting Friction and Equilibrium

Practise modelling a particle about to slip, resolving to find the normal reaction and using F = μR with the correct impending-motion direction to solve coefficients or angle…

Exam points

infer the friction direction opposite the stated or impending relative motion
resolve perpendicular to the contact surface to calculate the normal reaction R
set F = μR only at limiting equilibrium and solve the remaining force or angle equation

[Maximum number: 3]

A particle P of mass 0.2 kg lies at rest on a rough horizontal plane. A horizontal force of 1.2 N is applied to P.

Given that P is in limiting equilibrium, find the coefficient of friction between P and the plane.

$R=0.2 \mathrm{~g}$

B1

$1.2=\mu \times 0.2 g$

M1

Resolve horizontally and using
$F=\mu R$ to get an equation in $\mu ; 2$
relevant terms.

$\mu=0.6$

A1

ое

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4.1.6—Equilibrium question 1