# Homework Help: Springs, 2 Questions

1. Feb 3, 2010

### 54088

1.A stell spring has a spring constant of 25Nm^-1.Calculate
a.the extension of the spring when the tension in it is equal to 10N,
b.The tension in the spring when it is extended by 0.50m from its unstretched length.

2.Two identical stell springs of length 250mm are suspended vertically side-by-side from a fixed point. A 40N weight is attached to the ends of the two springs. The length of each spring is then 350mm. calculate:
a. The tension in each spring,
b. The extension of each spring.
c. The spring constant of each spring.

2. Feb 3, 2010

Any attempts?

3. Feb 3, 2010

### 54088

By using Hooke's law F = kL......
a. 10 = 25 x L, L = 0.4m
b. F = 25 x 0.5 = 12.5N

Last edited: Feb 3, 2010
4. Feb 3, 2010

Looks good.

5. Feb 3, 2010

### 54088

but i don't know how to do question 2?
a. 40/2 = 20N
b. 350mm - 250mm = 100mm
c. 20 = 350k...?????

Last edited: Feb 3, 2010
6. Feb 3, 2010

### HallsofIvy

Yes, of course. (Note that you were told the two springs were identical.)

Good.

No, it is the extension that is important: 20= 100 k.