**Moderators:** MelissaB, kgudger, Ray Trent, Moderators

3 posts
• Page **1** of **1**

I built a model of the knee to measure the stress put on the patella. To do so, I must use hooke's law. I under stand that in f=-kx, x is the distance, but how do I find the k variable? The k variable being the spring constant of the spring...how do I find it? Please please please help! My project is due on Jan 24th!

- vancan007
**Posts:**3**Joined:**Mon Jan 13, 2014 9:35 pm**Occupation:**student**Project Question:**measuring knee stress with a mechanical model**Project Due Date:**January 27, 2013**Project Status:**I am conducting my experiment

Hi vancan007,

To calculate the spring constant, k, you will need to measure the force you apply to the spring to stretch the spring by a certain distance. Then, plug the force and distance into Hooke's law and solve for k. For example, let's say that I applied 10 Newtons of force to the spring, and the spring extended by 20 cm. Since

f = -kx

-f/x = k

-10 newtons/0.2m = k

k = -50 Newtons/meter

To calculate the spring constant, k, you will need to measure the force you apply to the spring to stretch the spring by a certain distance. Then, plug the force and distance into Hooke's law and solve for k. For example, let's say that I applied 10 Newtons of force to the spring, and the spring extended by 20 cm. Since

f = -kx

-f/x = k

-10 newtons/0.2m = k

k = -50 Newtons/meter

All the best,

Terik

Terik

- Terik Daly
- Expert
**Posts:**1018**Joined:**Sat Nov 08, 2003 11:27 pm**Occupation:**Planetary Scientist**Project Question:**N/A**Project Due Date:**N/A**Project Status:**Not applicable

Thank you so much!

- vancan007
**Posts:**3**Joined:**Mon Jan 13, 2014 9:35 pm**Occupation:**student**Project Question:**measuring knee stress with a mechanical model**Project Due Date:**January 27, 2013**Project Status:**I am conducting my experiment

3 posts
• Page **1** of **1**

Return to Grades 9-12: Physical Science

Users browsing this forum: Bing [Bot], Google [Bot] and 6 guests