Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A block with mass $5\text{ kg}$ is dragged across a rough level floor by a force of magnitude $X\text{ N}$ acting at $30^\circ$ above the horizontal (see diagram). It starts from rest and covers $2\text{ m}$ in the first $5\text{ s}$ of its motion.
(a)[2]
Find the acceleration of the block in this situation.
(b)[4]
When the coefficient of friction between the block and the floor is $0.4$, determine $X$.
(c)[3]
The block is now on a different section of the floor where the coefficient of friction between the block and the floor has another value. The value of $X$ is altered to $25$, and the block is now in limiting equilibrium. Find the coefficient of friction between the block and this section of the floor.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply $s=ut+\frac12at^2$ using $s=2$ and $t=5$.” …