# Measurement of Young modulus of iron

Extracts from this document...

Introduction

903101.doc p./

Mok Man Hin 7B (19)

D2 Measurement of Young modulus of iron

### Objective

To find out the Young modulus of iron by adding water into the water bucker to increase the load of the iron wire held. Record the extension of the wire at difference mass of load and plot out a graph of the extension of the iron wire against the mass of the load to find out the Young modulus of the iron wire.

### Procedure

1. Measure the diameter of an iron wire at three different points along its length by a micrometer screw gauge. Take the mean value. Calculate its cross-sectional area (A).

Data 1 | Data 2 | Data 3 | Mean | |

Diameter of iron wire / mm | 1.15 | 1.17 | 1.16 | 1.16 |

Cross-sectional area (A) = _____1.0568 x 10-6_m2________________________________

3. Measure the distance between the wooden blocks and the sticker, i.e. the unstretched original length () of the copper wire.

Unstretched original length () = ___2.42m_____________________________________

4. Add 500c.c. of water as load (m)

Middle

0.143

6. Plot a graph of the extension (e) of the iron wire against the mass of the load (m). Find the slope of the graph.

Apparatus

Iron wire x1 (2.42m) | Camera x 1 |

Half- miler Ruler x1 (66.1g) | Large Water bucket x2 (869.1g) |

Water | 500 ml Beaker x1 |

Measuring tape x1 | Hook x1 |

Safety goggles x1 | Miler Ruler x1 |

Mass of water bucker and the ruler = 0.9352kg

Mass of load added each time = 500/1000 = 0.5 kg

### Theory

When a force is applied to a body, it deforms. By Hooke’s Law, within elastic limits, the extension or compression (e) of the object is directly proportional to the force applied (F)

Stress = Force (F) /Cross-section area (A) and Strain = Extension (e) / Original length (l)

Young modulus (E) = Stress / Strain = Fl / Ae

= mgl/Ae

Results and Discussion

- Describe the shape of the graph of extension against load in step 6. Which part of the graph obeys Hooke’s Law?

Conclusion

5. Give a conclusion to this experiment.

The iron wire obeys the Hooke’s Law from 0 kg to 10 kg with elastic limit at 9.462243941 x 107 Pa. The young modulus of this iron wire is approximately at 2.16 x 109 Pa. The result is not accurate due to the amount of water added is not constant and the reading of extension is not correct due to the reading error.

New Way Physics for Advanced Level © Manhattan Press 2005

This student written piece of work is one of many that can be found in our AS and A Level Fields & Forces section.

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