Newton's third law and connected particlesEdexcel A-Level Maths: Mind map

Exam questions on Newton's third law and connected particles

1. A lift of mass 250 kg carries a person of mass 70 kg. The lift is raised by a vertical cable and accelerates upwards at $1.5\ \text{m s}^{-2}$. Take $g=9.8\ \text{m s}^{-2}$.
   Find the tension in the cable.2 marks
2. Particle $A$ of mass 3 kg and particle $B$ of mass 5 kg are attached to the ends of a light inextensible string that passes over a smooth fixed pulley. The particles hang vertically and are released from rest with the string taut. Take $g=9.8\ \text{m s}^{-2}$.
   Particle $B$ is initially 1.5 m above the floor. Find the speed with which $B$ hits the floor.2 marks
3. Two blocks, $P$ of mass 4 kg and $Q$ of mass 6 kg, are in contact on a horizontal surface. A horizontal force of magnitude 30 N is applied to $P$, directed towards $Q$, and the blocks move together in a straight line.
   The surface is smooth. Find the acceleration of the blocks and the magnitude of the contact force between them.3 marks