# Springs - Hooke's Law

How do i find the force constant of a spring with a Newton meter?
Do i graph the force applied vs. distance of stretch? What is on the x-axis, what is on the y-axis?

How do i find an equation for the amount of skretch needed for on spring on a projectile, with the horizontal distance, angle of the projectile, mass and force constant given?

## Answers and Replies

What kind of text book are you using in your school?

ShawnD
Science Advisor
Originally posted by marshall4
How do i find the force constant of a spring with a Newton meter?
Do i graph the force applied vs. distance of stretch? What is on the x-axis, what is on the y-axis?
F = kd
k = F/d
Now that you know the formula, it's easy to figure it out. Plot force on the Y axis and displacement on the x axis. The slope of the graph will give you the k value.

Your second question is difficult to understand. Can you reword it or say it differently?

Originally posted by PiRsq
What kind of text book are you using in your school?

Nelson Physics 12
Why?

Originally posted by ShawnD

Your second question is difficult to understand. Can you reword it or say it differently?

I'm launching a spring off the end of an angled launch pad (projectile) at angle Өtheta, i want to find how long i have to skretch the spring in order for the spring to go x metres in the horizontal distance.

i think i use the equation ½mv²=½kx² to find the velocity. Then I use that velocity in the equation d=[v²sin2(theta)]/g, to find the horizontal distance. Does that sound right, or is there an easier equation?

Last edited:
Combine the equations to get the result

Range = (kx2 sin 2&theta;)/mg

I can't see it getting any easier.

Checkout Sample Problem #4 on pg 209