# Forces: Springs

## Forces: Springs

### Hooke’s Law:

**Hooke’s Law**states that the force needed to extend or compress a spring by a certain distance is proportional to that distance.- This means that the extension or compression of a spring is directly proportional to the applied force, as long as the elastic limit isn’t exceeded.
- The formula for Hooke’s Law is:
**Force (N) = spring constant (k) x extension (m)**.

### Spring Constant:

- The
**spring constant**, denoted by the symbol k, is a measure of the stiffness of a spring. - It is the force required to extend the spring by one metre.
- The spring constant is measured in newtons per metre (N/m).
- A high spring constant indicates a stiff spring, whereas a low spring constant indicates a less stiff, or more stretchy, spring.

### Elastic Limit:

- The
**elastic limit**of a spring is the maximum amount it can be extended or compressed without permanently deforming it. - When a spring is stretched beyond its elastic limit, it will not return to its original length when the force is removed, and the spring is said to be permanently deformed or the spring has been stretched to the point of plastic deformation.

### Elastic Potential Energy:

- When a force is used to extend or compress a spring,
**elastic potential energy**is stored in the spring. This is energy that can be recovered when the spring returns to its original shape. - The formula for elastic potential energy is:
**Elastic potential energy (J) = 0.5 x spring constant (k) x (extension (m))^2**.

### Extension and Compression:

- Extension is how much a spring is stretched from its original length.
- Compression is how much a spring is squeezed from its original length.
- If a spring obeys Hooke’s Law, a graph of force versus extension or compression will be a straight line passing through the origin up to the point of the elastic limit.