Help Me Spring Constant & Potential Energy

[davidliebehar]

Here is a very basic question that I need help with.

Homework Statement

A spring has a spring constant (k) of 82 N/m. How far must the spring be compressed to store 35J of potential energy?

Homework Equations

I think it is: E = 1/2 kx^2

The Attempt at a Solution

I don't understand how to setup this problem. Please help me.

 

[LowlyPion]

Here is a very basic question that I need help with.

Homework Statement

A spring has a spring constant (k) of 82 N/m. How far must the spring be compressed to store 35J of potential energy?

Homework Equations

I think it is: E = 1/2 kx^2

The Attempt at a Solution

I don't understand how to setup this problem. Please help me.

Welcome to PF.

Let's see. You have the equation. They tell you what E is. They tell you what k is ... so you're having trouble solving for x?

 

[davidliebehar]

yes.
should the equation look like this?
35J = 1/2 (82 N/m) x^2

 

[LowlyPion]

yes.
should the equation look like this?
35J = 1/2 (82 N/m) x^2

Just solve for X.

 

[davidliebehar]

I don't know how to.
is 82 N/m the same as 82 J?would I get

35J divided by 41 N/m = x^2? then x = square root of 35J divided by 41 N/m?

 

[LowlyPion]

I don't know how to.
is 82 N/m the same as 82 J?

would I get

35J divided by 41 N/m = x^2? then x = square root of 35J divided by 41 N/m?

No N/m is a spring constant. It moves 1 meter for every 82 Newtons of force.

Joules are units of what? N-m? and you are dividing by N/m? that yields m² and x² is m² ... so everything is right.

As to your calculation ... that's right.

 

[davidliebehar]

i don't know whAt to do
plaese show me exactly how to solve this problem and all the steps i am so lost

 

[LowlyPion]

35J divided by 41 N/m = x^2? then x = square root of 35J divided by 41 N/m?

Look. You've already solved it ... that is if you meant to divide 35 by 41 before you took the square root.

 

[davidliebehar]

i just want an answer in meters.

 

[LowlyPion]

i just want an answer in meters.

That gives you an answer in meters.

 

[davidliebehar]

(sqaure root of 35j divided by 41 N/m) meters?

 

[LowlyPion]

(sqaure root of 35j divided by 41 N/m) meters?

sqaure root of (35j divided by 41 N/m) meters?

Yes. I already showed you that you get m² before you take the square root.

 

[davidliebehar]

thanks for your help, but i still can't understand this, i'll have to ask my instructor.