[填空题]
Designers of today’s c; 1 jje447 v0iy8;earnd-6drt ogt) d q1ydckgars have built “5mi/h(8km/h) bumpers” that aj za/ owir4t73re designed to compress and rebound elastically without any physical damage at speeds below 8km/h If the material of the bumpers permanently deforms after a compression of 1.5 cm, but remains like an elastic spring up to that point, what must the 4o 7z/jatri3w effective spring stiffness constant of the bumper be, assuming the car has a mass of 1300 kg and is tested by ramming into a solid wall? $a\times10^b$ N/m a = b =
