Posted by Angel on .
The body of a 1269 kg car is supported on a
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?

Physics 
bobpursley,
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)