A heavy-duty cable lift in a mining facility consists of a cargo hopper, AAA, and a solid steel counterweight, BBB, connected by a light inextensible cable. The hopper A A\,A has a mass of 80 kg and is positioned on a rough track inclined at 60∘ 60^\circ\,60∘ to the horizontal. The cable passes over a smooth pulley at the top of the track, and the counterweight BBB, which has a mass of 120 kg, hangs freely.
The system is released from rest with the cable taut and parallel to the line of greatest slope. The counterweight B B\,B descends with acceleration a a\,a m s−2^{-2}−2 and the tension in the cable is T T\,T Newtons.
Explain why the equation of motion for the counterweight B B\,B is 120g−T=120a120g - T = 120a120g−T=120a.
Show that the normal reaction force, RRR, between the hopper A A\,A and the track is 40g Newtons.
The coefficient of friction, μ\muμ, between the hopper A A\,A and the track surface satisfies 0≤μ≤0.50 \le \mu \le 0.50≤μ≤0.5. Show that
a≥(5−23)g10 a \ge \frac{(5 - 2\sqrt{3})g}{10} a≥10(5−23)gState one modelling assumption used in this problem regarding the cable or pulley.
130 exam-style questions on Edexcel A Level Maths Applications of Forces, covering 7.1 Static Particles, 7.2 Modelling with Statics, 7.3 Friction and Static Particles, 7.4 Static Rigid Bodies, 7.5 Dynamics and Inclined Planes, and 7.6 Connected Particles 2. Each one has a worked solution and a mark scheme showing where the marks go.