Force Constant k of Spring - Potential Energy Homework

[themadhatter1]

Homework Statement

A spring is compressed a distance of 1m and a 2 kg rock is shot straight up with the spring. The rock attains a maximum height of 500m. What is the force constant k of the spring?

Use g=10m/s^2

Homework Equations

P.E.= mgh
P.E. elastic= (1/2)(k)(x^2)

The Attempt at a Solution

P.E.= mgh
P.E.=(2000g)(10m/s^2)(500m)
P.E.= 10000000 Newtons

P.E. elastic= (1/2)(k)(x^2)
k= P.E elastic/ (1/2)(x^2)
k= 10000000/ (1/2)(1)
k=2000000 Newtons ?

 

[Fightfish]

P.E.= mgh
P.E.=(2000g)(10m/s^2)(500m)
P.E.= 10000000 Newtons

Use SI units ie kilogram, not gram. Furthermore, energy is in joules, not Newtons! Also, the spring constant k is in Newtons per meter, not Newtons. Please read up on units, okay?

 

[themadhatter1]

Use SI units ie kilogram, not gram. Furthermore, energy is in joules, not Newtons! Also, the spring constant k is in Newtons per meter, not Newtons. Please read up on units, okay?

Thanks,

So, if I correct my units I would have:

P.E.= mgh
P.E.=(2kg)(10m/s^2)(500m)
P.E.= 10000 joules

P.E. elastic= (1/2)(k)(x^2)
k= P.E elastic/ (1/2)(x^2)
k= 10000/ (1/2)(1)
k=20000 N/m ?

Is this correct?

 

[Fightfish]

Looks good; that is one very strong spring indeed.