Wheel A has a radius 40cm with a pinion radius 10cm, wheel B has a radius 30cm with a pinion radius 15cm and wheel C has a radius 50cm. It is required to lift a weight of 22400 newtons with a pull of 400 newtons. What should the diameter of wheel C be to achieve this? Please show how you achieve the answer

In order to lift 22400 Newtons with only 400 newtons of force, you need a force multiplication of 22400/400 = 56 times. Wheel A has an outer radius 4 times greater than its pinion radius, so it should provide 4x force multiplication. Wheel B has an outer radius twice its pinion radius so it should provide an additional 2x force multiplication (for a total of 8x between wheels A and B). To get to a total of 56x, the remaining wheel has to provide an additional 56/8 = 7x force multiplication. Therefore, if its pinion radius is 50cm, its outer radius must be 7 times that big or 350 cm. Since your question was the diameter (not the radius) of wheel C, the answer is 700 cm.