# Spring Constant

Q. An object of mass o.4kg slides at 8m/s across a frictionless path before striking one end of a spring that is fixed at the other end. the spring constant is 80N/m. the maximum distance, in metres, by which the spring compressed is : ans?

I a not sure wether to use hookes law (f=ks) or the kinetic energy formula Ek = .5kmv^2

when i used hookes law i got an answer of 0.04 but when i use the kinetic energy forumla i got 0.57. I know it doesnt really make any sense to use hookes law as u cant find the force, only the momentum (0.4x 8)

any help with this would be greatly apreciated

## The Attempt at a Solution

Doc Al
Mentor
It sounds like you're answering your own question. so its the kinetic formula cos it wouldnt make sense to use the hookes law right? but since when can u have the spring constant in a kinetic energy formula?

Doc Al
Mentor
so its the kinetic formula cos it wouldnt make sense to use the hookes law right?
Yes, you'll need to use energy conservation.
but since when can u have the spring constant in a kinetic energy formula?
Consider the potential energy stored in a compressed spring--that's where the spring constant appears.

cheers buddy