Question

An ideal spring with spring constant k is hung from the ceiling and a block of mass M is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is

• A. 4Mg/k
• B. 2Mg/k
• C. Mg/k
• D. Mg/2k

Answer 1

Answer: (B)

2Mg/k

Answer 2

Here P.E. = $\frac { 1 } { 2 }$ kx²

i.e., mgx = $\frac { 1 } { 2 }$ kx²

or x = 2mg/k