A 1200 kg car carrying four 82 kg people travels over a rough quot;washboardquot; dirt road with corrugations 4.0 m apart which causes the car to...

A 1200 kg car carrying four 82 kg people travels over a rough "washboard" dirt road with corrugations 4.0 m apart which causes the car to bounce on its spring suspension. The car bounces with maximum amplitude when its speed is 18 km/h. The car now stops, and the four people get out. By how much does the car body rise on its suspension owing to this decrease in weight?