Question

A 4.0-kg red book is suspended from a spring attached to the ceiling of an elevator that is accelerating downward. Attaching the book causes the spring to stretch 71 mm beyond its relaxed length. You also have a yellow book of unknown inertia. When you attach the yellow book and the red one to the spring at the same time, the spring stretches 110 mm beyond its relaxed length. When the elevator is at rest, the combination of the two books stretches the spring 140 mm beyond its relaxed length. What is the spring constant?

Answer 1

Spring constant is 433.8 N/m