12:48 Task 1 L3 Dynamics Assignment... Problem 1 D Load = W axel Mass lifted wheel W + Effort = E E Side view Front view Figure 1 In a wheel and axle machine as shown in Figure 1 the diameters of the wheel and the axle are 450mm and 60mm respectively. The efficiency is 97% (0.97 per unit) when a body having a mass of 40kg is being lifted. Determine the following dynamic and kinetic parameters of this lifting system. (take g = 9.81 m/s) i. velocity ratio ii. actual mechanical advantage iii. actual effort Problem 2 A screw jack has a single start thread of pitch 6mm and an operating handle of radius 350 mm as shown in Figure 2. The following readings of load and effort were taken during a test on the jack. Single start thread, pitch 6 mm Operating handle length 350 mm Figure 2 Load 0 1 2 3 4 5 6 7 8 9 10 (KN) Effort 2.2 6.6 11.8 17.0 22.2 27.2 32.2 36.8 41.4 46.9 52.4 (N) (a) Plot a graph of effort against load. Using the graph determine the law of the machine. (b) Plot a graph of mechanical advantage against load. (c) Plot a graph of efficiency against load and state whether the machine is likely to overhaul. (d) Evaluate the theoretical limiting values of mechanical advantage| and efficiency and explain whether your graphs tend towards these values. (e) Calculate the work input and the work done against friction when raising the 10 kN load through a height of 50 mm.