What is the spring constant of spring?

[Mdhiggenz]

Homework Statement

A 60 kg person drops from rest a distance of 1.20 m to a platform of negligible mass supported by a stiff spring. The platform drops 6 cm before the person comes to rest. What is the spring constant of spring?

Homework Equations

The Attempt at a Solution

w=1/2kx^2

mgh=1/2kx^2

2(mgh)/x^2=k

2(60kg*9.8*1.20)/0.06m=3.92*10^5

the answer however is 4.12*10^5


What am I doing wrong?

Thank you

 

[Delphi51]

The mass falls further than 1.20 as the spring compresses.

 

[Mdhiggenz]

So would I add the 0.06m? Iam a bit confused

 

[tiny-tim]

Correct.

The question says …

A 60 kg person drops from rest a distance of 1.20 m to a platform

… after that it drops a further 0.06 m, so the total drop (for the person) is 1.26 m

 

[Mdhiggenz]

Thx Tim