physics mechanics question (1 Viewer)

[velox]

You are asked to design spring bumpers for the walls of a parking garage. A freely rolling m car moving at v is to compress the spring no more than x before stopping.

What should be the force constant of the spring? Assume that the spring has negligible mass.

I thought it would be 1/2mv^2 / x but apparently that is not right. Anyone know what I should be doing?

 

[Nodice]

Use F=-kx=ma and v^2 = u^2 + 2as (u=v, v=0, s=x) to find your answer.

 

[SeDaTeD]

I think that would only work if the acceleration is constant.

It's been ages since I did physics, but equate the kinetic energy of the car with the elastic potential energy? I don't remember the formula for elastic potential energy though.