# Measuring Young modulus of copper

Extracts from this document...

Introduction

Physics TAS Full Report

D1:Measuring Young modulus of copper

19-10-2006

Aim

-To show that solid matter (copper wire) obeys Young modulus by finding the relationship between the load which is loaded at the end of the wire and extension of the copper wire.

-To show that solid matter (copper wire) obeys Hooke’s law in elastic deformation condition.

Apparatus

Copper wire | Slotted mass with hanger (0.1kg each) |

G-clamp | Adhesive label |

Wooden blocks | Micrometer screw gauge |

Half-meter ruler | Safety goggles |

Pulley on clamp |

Procedure

- A micrometer screw gauge is used to measure the diameter d of the wire at 2 or 3 different points along its length and is taken the mean value.
- The apparatus is set up on the bench as shown above. Be fixed an adhesive label on the wire as a marker.
- Original length l of the wire

Middle

0.7000

Failure

0.0060

0.0070

0.8000

Failure

0.0070

0.0090

0.9000

Failure

0.0145

0.0130

1.0000

Failure

0.0220

0.0320

1.1000

Failure

0.0430

0.0530

1.2000

Failure

0.0785

0.0795

1.3000

Failure

0.1190

0.1270

1.4000

Failure

0.1720

0.1650

4. Graphs of load against extension

-1st measurement (failure)

-2nd measurement*

-3rd measurement*

* The red points are the centroids of slope of straight line

5. Estimation of the elastic limit from the graphs

%strain = (extension/original length) x 100%

1st measurement | 2nd measurement | 3rd measurement | |

%strain | Failure | 6.5152 | 4.3732 |

- Measurement of slope of the graphs

Slope of graph = load/extension

1st measurement | 2nd measurement | 3rd measurement | |

Slope of graph (+0.0996kgm-1) | Failure | 114.2857 | 100 |

- Young’s modulus of copper calculation

E = slope of graph x (4gl/πd2) where g=10ms-1

1st |

Conclusion

(VI)

There was a small space in the pulley that the wire which was measured the

extension may not been in straight.

Conclusion

The 1st measurement is failure because the length of the wire is measured after the hanger is loaded at the end of the wire. Therefore, the experiment result is not accurate because the length of the wire is included the extension with the hanger.

The 2nd and 3rd measurements are proved that copper wire obeys Young modulus and Hooke’s law in elastic deformation condition. The stress (or the load) of the wire was directly proportional to the strain (or the extension) of the wire in elastic deformation. The deformation is remained elastic when the wire is loaded 0.8kg (elastic limit) of slotted masses in the graph shown. The yield point was the wire which is loaded 0.9kg slotted masses. The breaking stress of the copper wire was 1.4kg in both measurements.

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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