Units and Conversions You may find the following units and conversions helpful. Metric system. Work is measured newton-metres (N - m) or joules (J). One joule is one newton-metre. Force, as well as weight, is measured in newtons (N). The weight of an object is the force acting on the object due to gravity, calculated by the formula weight = mass X g. The constant of acceleration due to gravity is g. Its unit is metres per second squared (m/sz). You may use the approximation g ~ 9.8 m/s?. Mass is measured in kilograms (kg). The density of water is 1 kg/L. Volume is measured in litres L. 1m?is 1000 L. Length is measured in metres (m). One centimetre is 0.01 metre. One millimetre is 0.001 metre. US Customary system. Work is measured in pound-foot (Ib-ft). Force, as well as weight, is measured in pounds (lb). Length is measured in feet (ft). A 5 kg weight is attached to the bottom of a 9-metre long rope, which dangles out a window. Assume the weight does not touch the ground. The rope alone has a mass of 15 kg. How much work does it take to pull the entire rope through the window, together with the weight? Assume work is measured in newton-metres (N - m). Use a calculator to find a numerical approximation of your final answer to 2 decimal places. For example, if your final answer is 7, then you should enter 3.14 in the box below. In tests and the final exam, you will NOT need to approximate your final answer numerically