# Experiment to measure deflection when a force is applied to a cantilever.

Mukwinda Phiri                Physics

Sc1 Investigation – bending of a Cantilever.

Experiment to measure deflection when a force is applied to a cantilever.

## Introductory Diagram

Aim

To find out whether varying the load has any affect on the deflection (∆d) of the ruler.

## Theory

Elasticity is the property, which allows a material to regain its shape after being distorted.  Some materials like, rubber bands, are much more elastic than others.  The elastic limit of a material is the maximum amount by which it can be stretched and still regain its original shape after the distorting forces are removed.  If a material is stretched beyond its elastic limit its shape is permanently changed.

‘ The deformation of a material is proportional to the force is applied to it, provided the elastic limit is not exceeded’.  This is known as Hooke’s Law, named after its discoverer, Robert Hooke, a 17th century scientist.

Young’s Modulus

When stress is applied to a material, strain is produced in the material.  The strain is proportional to the stress, provided the stress does not exceed a limit known simply as the ‘limit of proportionality’.  Within this limit, the value of is a constant for that material, and is known as the Young Modulus for the material.

The Young Modulus (E) =

Provided the limit of proportionality is not exceeded.

Before we can work out the Young Modulus we need to know about stress and strain.  Stress is defined as the tension (force) ...