When a 81.0 kg. person climbs into an 1400 kg. car, the car's springs compress vertically 1.5 cm. What will be the frequency of vibration when the car hits a bump? (Ignore damping.)

Answer 1

f = (1/2pi)*sqrt(k/M) Hz

M = 1481 kg
k = 81*9.8/0.015 = 52900 N/m

f = 5.0 Hz.