# Graph and Solve Inequality

• Aug 4th 2006, 06:53 AM
Graph and Solve Inequality
A spring has an unstretched length of 10cm. When it is hung with a load of 80g attached, the stretched length is 28 cm. Assuming that the extension of the spring is proportional to the load:
(i) draw a graph of extension E against load L and find its equation.
(ii) find the load required to extend the spring to a length of 20 cm.
This particular spring passes its elastic limit when it is stretched to four times its original length.
(iv) Find the load which would cause this to happen.

Thank You
• Aug 7th 2006, 07:04 AM
Quick
Quote:

A spring has an unstretched length of 10cm. When it is hung with a load of 80g attached, the stretched length is 28 cm. Assuming that the extension of the spring is proportional to the load:
(i) draw a graph of extension E against load L and find its equation.
(ii) find the load required to extend the spring to a length of 20 cm.
This particular spring passes its elastic limit when it is stretched to four times its original length.
(iv) Find the load which would cause this to happen.

Thank You

I'll start you off (tell me if I've got some kind of misconception),

you know two points on the graph: (0,10) and (80,28)

use that information to find the equation.

once you have the equation, substitute 20 for y (or f(x), whichever you prefer) and solve for x

to find the load that makes the spring reach it's limit, substitute 40 for y and solve for x
• Aug 7th 2006, 05:39 PM
Quote:

Originally Posted by Quick
I'll start you off (tell me if I've got some kind of misconception),

you know two points on the graph: (0,10) and (28,80)

Umm in the first point, you've taken Extension as the Y co-ordinate but in the second point extension is on the X-Axis??
Quote:

Originally Posted by Quick
once you have the equation, substitute 20 for y (or f(x), whichever you prefer) and solve for x
to find the load that makes the spring reach it's limit, substitute 40 for y and solve for x

Here again the Extension is taken on the Y-Axis so I am guessing that the second point should ideally read as (80,28)???
• Aug 7th 2006, 06:00 PM
Quick
I'm sorry bout that, I've fixed my last post.