# Can you help me with springs?

• June 30th 2006, 12:29 PM
LLELLA
Can you help me?
1.Consider a plot of the displacement on the y-axis vs. applied force on the x-axis for an ideal elastic spring. the slope of the curve would be:
a) the spring constant.
b) the reciprocal of the spring constant.
c) the reciprocal of the acceleration of gravity.
d) the acceleration of gravity.

2. A 10.0 kg mass hung onto a spring, causes the spring to stretch 2.0 cm the spring constant is.
a) 49 N/cm
b) 20.0 N/cm
c) 5.0 N/cm
d) 0.020 N/cm
e) 0.20 N/cm
• July 1st 2006, 12:18 AM
earboth
Quote:

Originally Posted by LLELLA
1.Consider a plot of the displacement on the y-axis vs. applied force on the x-axis for an ideal elastic spring. the slope of the curve would be:
a) the spring constant....

2. A 10.0 kg mass hung onto a spring, causes the spring to stretch 2.0 cm the spring constant is.
a) 49 N/cm...

Hi, LLELLA,

with a ideal elastic spring the force F and the displacement d are proportional:
$\frac{F}{d}=s\ \mbox{constant value, specific property of the spring}$
From $\frac{F}{d}=s\Longrightarrow F(d)=s\cdot d$

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:
$F=a\cdot m\Longrightarrow F=9.81\frac{m}{s^2}\cdot 10 kg=98.1 N$
Use the formula given above to calculate the spring constant s. Plug in the values you know and solve for s:

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

Bye

EB
• July 1st 2006, 04:39 AM
topsquark
Quote:

Originally Posted by earboth
Hi, LLELLA,

with a ideal elastic spring the force F and the displacement d are proportional:
$\frac{F}{d}=s\ \mbox{constant value, specific property of the spring}$
From $\frac{F}{d}=s\Longrightarrow F(d)=s\cdot d$

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:
$F=a\cdot m\Longrightarrow F=9.81\frac{m}{s^2}\cdot 10 kg=98.1 N$
Use the formula given above to calculate the spring constant s. Plug in the values you know and solve for s:

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