The body of a 1269 kg car is supported on a

Question

frame by four springs. The spring constant of
a single spring is 2.75 × 10
4
N/m. Four people riding in the car have a combined mass
of 256 kg. When driven over a pothole in
the road, the frame vibrates and for the first
few seconds the vibration approximates simple harmonic motion.
What is the period of vibration of the car?

Answer 1

when springs are in parallel, the following happens:

F/4=kx
k=F/4x which is exactly 1/4 of the original k.

so here the combined spring constant then is 2.75E4 /4

mass total...you do it.

F= 1/2PI sqrt (k/m)
and
t=1/F= 2PI sqrt (m/k)