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pizza1512
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Hi there! Can anyone help me with a problem.
I did an experiment at school trying to measure the Young's modulus of a copper wire. We attached one end of the copper wire to a clamp and then tied on weights of 100g at a time to the other end so that a force can be applied to the copper wire and so it stretches.
To work out Young's modulus, we require two things: the stress and the strain of the wire.
Stress is \sigma = \frac{F}{A} and strain is \varepsilon = \frac {\delta \ell}{\ell_o} \frac {change in length}{original length}.
To work out Stress, I worked out the Force applied on the wire by the weights (using the equation Force = Mass \times Gravitational potential energy) as 0.1kg \times 10 and this in turn produces 1N of force everytime a weight is added. To work out the area of the copper wire, I measured the diameter using a micrometer and this gave me an measurement of d=0.35mm. From this I worked out the cross section of the wire:
\frac{0.35}{2} (to find the radius), then squaring this and multiplying by \pi to obtain the area.
For stress I measured the original length of the wire (337cm) and then measured the extension of the wire and then dividing this by the original length.
My results table is attached.
When I try and plot the graph, I end up with a curved graph so the Young's modulus is not a straight line and so is the not directly proportional. Can anyone help me and tell me what I have done wrong in my experiment or is a curved line correct? Are my results alright?
Thanks
:shy:
I did an experiment at school trying to measure the Young's modulus of a copper wire. We attached one end of the copper wire to a clamp and then tied on weights of 100g at a time to the other end so that a force can be applied to the copper wire and so it stretches.
To work out Young's modulus, we require two things: the stress and the strain of the wire.
Stress is \sigma = \frac{F}{A} and strain is \varepsilon = \frac {\delta \ell}{\ell_o} \frac {change in length}{original length}.
To work out Stress, I worked out the Force applied on the wire by the weights (using the equation Force = Mass \times Gravitational potential energy) as 0.1kg \times 10 and this in turn produces 1N of force everytime a weight is added. To work out the area of the copper wire, I measured the diameter using a micrometer and this gave me an measurement of d=0.35mm. From this I worked out the cross section of the wire:
\frac{0.35}{2} (to find the radius), then squaring this and multiplying by \pi to obtain the area.
For stress I measured the original length of the wire (337cm) and then measured the extension of the wire and then dividing this by the original length.
My results table is attached.
When I try and plot the graph, I end up with a curved graph so the Young's modulus is not a straight line and so is the not directly proportional. Can anyone help me and tell me what I have done wrong in my experiment or is a curved line correct? Are my results alright?
Thanks
:shy:
Last edited:
