The safety mechanism for an elevator involves a suspension spring at the bottom of the elevator shaft and a safety clamp which applies a constant 17000N frictional force to the elevator. The spring should have a spring constant so that it is able to stop the elevator over a compression distance 2.00m

If the 2000kg elevator is falling at 4m/s when it first comes into contact with the spring what should the force constant of the spring be?

i am not sure if i should consider the Work with regards to gravity or just use energy from kinetic energy to solve.

Question

The safety mechanism for an elevator involves a suspension spring at the bottom of the elevator shaft and a safety clamp which applies a constant 17000N frictional force to the elevator. The spring should have a spring constant so that it is able to stop the elevator over a compression distance 2.00m

If the 2000kg elevator is falling at 4m/s when it first comes into contact with the spring what should the force constant of the spring be? 

i am not sure if i should consider the Work with regards to gravity or just use energy from kinetic energy to solve.