# Hooke's law - Natural Extension of Spring

1. Apr 18, 2014

### Emz19

Can I find out the natural extension of a spring if I am only given the mass of a block that can be put on it and the value of the spring constant? I have found x ( from the formula F = -kx ) when the block is on it but I now need to find the extension of the spring with no mass on the end. It is probably really simple but I am just a little stuck! Thanks

2. Apr 18, 2014

### ModusPwnd

With no mass attached, what is F? Plug that value in and solve for x. Or am I missing something?

3. Apr 18, 2014

### Emz19

well I thought with no mass the force is zero but then is the k equal to x? See, i was getting a big answer then for x and it didnt seem like the right answer. I am definitely missing something very obvious here

4. Apr 18, 2014

### paisiello2

How heavy is the spring itself? Is the spring vertical or horizontal?

5. Apr 18, 2014

### Emz19

The spring is vertical and the question does not give the mass of the spring.

6. Apr 18, 2014

### ModusPwnd

No, k is not equal to x in that case. Recall your algebra, you have to do the same thing to both sides to isolate the variable you want. Solve for x by doing the same thing to both sides then plug in 0 for mass/force (you can plug in the zero first, but its usually easier to solve first then plug in).

7. Apr 18, 2014

### Emz19

Ok great, thanks a mill :)