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Show that the smallest possible value of $X$ is $23.1$, correct to $3$ significant figures, and find the greatest possible value of $X$.
Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A particle of mass $15\,\text{kg}$ rests stationary on a rough plane inclined at an angle of $20^\circ$ to the horizontal. The coefficient of friction between the particle and the plane is $0.2$. A force of magnitude $X\,\text{N}$, applied parallel to a line of greatest slope of the plane, is then used to keep the particle in equilibrium.