Q. A block of mass M is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value k. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be:
A) 2 Mg/k
B) 4 Mg/k
C) Mg/2k
D) Mg/k
Explanation
[Solution from source] Released from rest with the spring unstretched, the block moves until it is momentarily at rest again. Energy conservation: Mgx = ½kx², so the maximum extension is x = 2Mg/k. Mg/k is only the equilibrium extension (where the block moves fastest), not the maximum. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.