the cable of a hoist has a cross-section of 80 mm2. the hoist is used to lift a crate weighing 500 kg. what is the stress in the cable? the free length of the cable is 3 m. how much will it extend if it is made of steel (modulus 200 gpa)?howmuchifitismadeofpolypropylene,pp(modulus1.2 gpa)?