Response: k = 23045 N/m
Clarification:
To determine the spring constant, one must consider the maximum elastic potential energy that the spring can withstand. The kinetic energy of the vehicle should equal at minimum the elastic potential energy of the spring when it is fully compressed. Hence, we express it as:
(1)
M: mass of the vehicle = 1050 kg
k: spring constant =?
v: car speed = 8 km/h
x: maximum spring compression = 1.5 cm = 0.015m
You need to resolve equation (1) for k. Beforehand, convert the speed v to meters per second:


The spring constant calculates to 23045 N/m
I believe the answer is D, though I'm not entirely certain unfortunately.