# What Determines the Stiffness of a Spring?

• fatboy_1989
In summary, stiffness is a characteristic of materials that is determined by the equilibrium spacing of atoms and the forces between them. It takes energy to stretch or compress a material, and the amount of energy required depends on the material's modulus of elasticity and its extension under a specific amount of force. Stiffness can come in different forms, including axial, bending, and torsional stiffness. For more information, further research can be done on the topic.
fatboy_1989
Does anybody know why a spring has a stiffness, does anyone know the physics behind it like the intermoleculaor bonds etc. This would be a great help as my coursework has to be handed in next week. Thanks

Hi fatboy_1989, welcome to PF. The atoms in any solid are spaced at an equilibrium distance from each other, at the balancing point between attraction and repulsion. (The attraction is electrostatic--electrons attracted to another atom's protons--and the repulsion is caused by the exclusion principle, if you've studied that.) The equilibrium spacing is the lowest-energy configuration, so it takes energy to stretch or compress it. When you stretch a spring, the work you are doing adds this energy.

thanks a lot very very appreciated

all materials have its stiffness. the strength of stiffness depends on the extension of the material under a definite amount of force ... the lower the extension, the stiffer the material is... in other words, it depends on the young modulus of spring, which is usally made of iron.
for forces between metallic atoms, it is usally consists of two kind forces - one with short-range repulsive force and that long-range attractive force.

for details, you can search on the internet or reference books.

Stiffness comes in many flavors. "Axial stiffness" $AE/L$ or "Bending Stiffness" $E I / L$, Torsional or Twisting $J G/ L$... The list goes on... By definition (as related to the solution of most problems) the stiffness is the amount of force it takes to deflect something (usually a solid) by 1 unit.

## 1. What is stiffness in the context of springs?

Stiffness in a spring refers to its ability to resist deformation or change in shape when a force is applied to it. In simpler terms, it is a measure of how difficult it is to stretch or compress a spring.

## 2. What factors contribute to the stiffness of a spring?

The stiffness of a spring is influenced by several factors, including its material, dimensions, and shape. The type of material used, such as steel or rubber, can greatly affect a spring's stiffness. Additionally, a spring with a larger diameter or shorter length will generally be stiffer than a thinner or longer spring.

## 3. How is stiffness measured in a spring?

The stiffness of a spring is typically measured in units of force per unit of length, such as pounds per inch or newtons per meter. This is known as the spring constant, which is a numerical value that represents the amount of force required to stretch or compress a spring by a certain distance.

## 4. Can the stiffness of a spring be changed?

Yes, the stiffness of a spring can be altered by changing its material, dimensions, or shape. For example, using a stiffer material or increasing the spring's diameter can increase its stiffness. Additionally, the number of coils in a spring can also affect its stiffness.

## 5. How does temperature affect the stiffness of a spring?

Temperature can have a significant impact on the stiffness of a spring. In general, as temperature increases, the stiffness of a spring decreases. This is because the molecules in the spring's material have more energy and are able to move more, making it easier to stretch or compress the spring. Some materials, such as rubber, are particularly sensitive to temperature changes and can experience a significant decrease in stiffness with even small temperature increases.

• Mechanics
Replies
4
Views
1K
• Mechanics
Replies
9
Views
1K
• Mechanics
Replies
8
Views
1K
• Mechanics
Replies
10
Views
2K
• Introductory Physics Homework Help
Replies
18
Views
969
• Mechanics
Replies
8
Views
847
• Classical Physics
Replies
4
Views
320
• Mechanics
Replies
9
Views
2K
• Mechanics
Replies
6
Views
1K
• Mechanics
Replies
26
Views
4K