How Long Does the Strong Force Take to Act on a Pion?

[Winzer]

Homework Statement

A pion traveling near the speed of light hits a nucleus and travels an average distance of 3.5fm before interacting. Estimate the time req. for the strong force to interact.

Homework Equations

The Attempt at a Solution

So are they saying that the pion hits the nucleus travels 3.5fm, then the strong force acts on it?
It would be kin. eqs. to solve then right?

 

[Winzer]

If they say it's near the speed of light i will have to use relativistic kin. I think.

 

[Hao]

This question is probably less complicated than it seems.

Assuming that the time it takes for the strong force to begin affecting the pion is measured from when the pion first touches the nucleus, and also assuming that all quantities are given for the lab frame,

we have time = distance / velocity.