Mathematics 9709 · AS & A Level · Newton's laws of motion
Newton's laws of motion — practice question
Particles $A$ and $B$, having masses $1.3\,\text{kg}$ and $0.7\,\text{kg}$ respectively, are linked by a light inextensible string passing over a smooth fixed pulley. Particle $A$ is positioned $1.75\,\text{m}$ above the floor, while particle $B$ is $1\,\text{m}$ above the floor (see diagram). The system is let go from rest with the string taut, and the particles travel vertically. When the particles are level with each other the string breaks.
(i)[4]
Show that, before the string breaks, the magnitude of the acceleration of each particle is $3\,\text{m}\,\text{s}^{-2}$ and find the tension in the string.
(ii)[6]
Find the difference between the times taken by the particles to reach the ground.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applies Newton’s Second Law to either particle, e.g. $1.3g - T = 1.3a$ or $T - 0.7g = 0.7a$” …