1. Hookes Law

2. Robert Hooke (also the guy who named the cell, cell), came up with something called Hookes law, that deals with springs.
His law is F = -kx, where F is the force exerted by the spring, k is the constant in a spring, and x or ∆x, is the distance it stretches measured in meters.
His law states : The force exerted by a spring is equal to the spring constant times the distance the spring is stretched or compressed from is equilibrium position.

3. Examples
A sack of potatoes is hanging from a spring. The potatoes weigh 56N and their weight causes the spring to stretch 18cm. What is the spring constant?
Known: 18cm = 0.18m, and weight is 56N
F=-kx
56=-k(0.18) ( we can drop the minus sign because that’s used for when the spring is restoring back to it’s position)
K= 311 N/m

4. How much force is needed to stretch a spring 0
How much force is needed to stretch a spring 0.25m when it’s constant is 95N/m?
F=95 x 0.25 = 23.75N (negative depending on the direction)
What is the spring constant when a 15kg ham is hung on a spring that goes 20cm?
Note: We had mass not weight!!! So 15 x 9.8 = 147N
147=k(0.2) so divide each side by 0.2 and we get 735 N/m