Could anyone help me with my Physics investigation? My friend and I have been working at this since Friday and haven't been able to figure it out. We've had so many problems with this experiment that I think we've just gone brain-dead or something
Anyway, this is the experiment, to investigate what sorts of materials make the best insulators and best conductors. We have a hotplate set at approximately 60 - 70 degrees with a temperature sensor to give us the exact temperature. We have a small beaker filled with honey (lower SHC than water to give us a more noticeable temp. change) and know the mass (approx. 30g). We have a temperature sensor in the honey as well.
We then record the starting temperatures of both the honey and the hotplate, and then place the insulating material and honey on the hotplate and start recording for 300 seconds with datalogger software so we get a graph over the whole time. At the end, we note the final temperature of the honey.
Our problems start when we have to do the maths. We have two equations:
Q = m c (t2 - t1) [1]
and
Q/t = (k (T2 - T1) A) / x [2]
(Fourier's Law pretty much)
The t's in [1] refer to the start and final temperatures of the honey (m and c are the mass and SHC of the honey, respectively). The t in [2] refers to the time (300s) and the T's in [2] refer to the starting temperatures of the honey and hotplate. The Q's are the same in both equations and we are using [1] to calculate Q for use in [2], the actual thermal conduction equation. k is the thermal conductivity of the particular material and what we are trying to find.
The types of materials we are using should give us values for k of round about 1, give or take a power of 10 or so. The problem is that we are getting values for k of around 0.001, even for things like aluminium which should be in the hundreds or thereabouts!
Attached is a calculation that we did for a ceramic tile, which gave a value for k of about 0.007... If anyone can help explain why we're getting such weird results, that would be greatly, greatly appreciated
Anyway, this is the experiment, to investigate what sorts of materials make the best insulators and best conductors. We have a hotplate set at approximately 60 - 70 degrees with a temperature sensor to give us the exact temperature. We have a small beaker filled with honey (lower SHC than water to give us a more noticeable temp. change) and know the mass (approx. 30g). We have a temperature sensor in the honey as well.
We then record the starting temperatures of both the honey and the hotplate, and then place the insulating material and honey on the hotplate and start recording for 300 seconds with datalogger software so we get a graph over the whole time. At the end, we note the final temperature of the honey.
Our problems start when we have to do the maths. We have two equations:
Q = m c (t2 - t1) [1]
and
Q/t = (k (T2 - T1) A) / x [2]
(Fourier's Law pretty much)
The t's in [1] refer to the start and final temperatures of the honey (m and c are the mass and SHC of the honey, respectively). The t in [2] refers to the time (300s) and the T's in [2] refer to the starting temperatures of the honey and hotplate. The Q's are the same in both equations and we are using [1] to calculate Q for use in [2], the actual thermal conduction equation. k is the thermal conductivity of the particular material and what we are trying to find.
The types of materials we are using should give us values for k of round about 1, give or take a power of 10 or so. The problem is that we are getting values for k of around 0.001, even for things like aluminium which should be in the hundreds or thereabouts!
Attached is a calculation that we did for a ceramic tile, which gave a value for k of about 0.007... If anyone can help explain why we're getting such weird results, that would be greatly, greatly appreciated