Spring suspension on car

[RIT_Rich]

Ok, here is the problem:

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 15 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?
--------
I know I'm supposed to find the spring constant of the suspension here and first I need to find the angular frequency...but how do I go about finding the angular frequency?

If anyone can help as soon as possible...thanks a lot

[gnome]

ω = 2Πf

(f you can get from the speed and the space between the bumps.)

Does that help?

[RIT_Rich]

How do you get f from the speed and the bumps?

I must have a really bad book...but it tells me that to get the frequency I need the angular frequency.

My book says f= w/2pi...which gives you w right back.

Thanks for the help

[gnome]

ω is the angular frequency (i.e. radians per second)

f is the linear frequency: cycles per second, bumps per second, bumps per minute, bumps per hour...

You have kilometers per hour and bumps per meter...

Got it?

Then, use
ω = 2Πf
to get the angular frequency.

Then use what you know about simple harmonic motion to get the spring constant.

[RIT_Rich]

Thanks a lot.