Originally Posted by **earboth**

Hi, LLELLA,

with a ideal elastic spring the force F and the displacement d are proportional:

$\displaystyle \frac{F}{d}=s\ \mbox{constant value, specific property of the spring}$

From $\displaystyle \frac{F}{d}=s\Longrightarrow F(d)=s\cdot d$

The graph of this function is a straight line with the slope s. So it's answer a).

To 2) I presume that you know that the force equals mass times acceleration. Plug in the values you know and you'll get:

$\displaystyle F=a\cdot m\Longrightarrow F=9.81\frac{m}{s^2}\cdot 10 kg=98.1 N$

Use the formula given above to calculate the spring constant s. Plug in the values you know and solve for s:

$\displaystyle \frac{F}{d}=s\Longrightarrow s=\frac{98.1N}{2 cm}\approx 49\frac{N}{cm}$

So it's answer a again.

Bye

EB