Today, multistorey buildings are common. To build a sky scrapper, we have to lift concrete, steel and other materials to a certain height. So, first they build a tower crane. One can see this crane near any tall building under constuction. First, let us understand the principle of this crane. Take a meter scale and hang it at the 50th cm. Take a 150 gm weight and hang it 10 cm (at 40 cm) from the centr...