The Potential energy stored in the system is 1 J
<u>Explanation:</u>
Given-
Mass, m = 4 kg
Spring constant, k = 800 N/m
Distance, x = 5cm = 0.05m
Potential energy, U = ?
We know,
Change in potential energy is equal to the work done.
So,

By plugging in the values we get,

Therefore, Potential energy stored in the system is 1 J
By collapsing and crumpling, the force and energy is absorbed by the crumple zone and it is not transferred to the passengers inside. This is a safety feature for the passengers.