In a mercury thermometer the capillary tube has a diameter of 0.0018 cm and the bulb has a diameter of 0.25 cm. Without the expansion of the glass how can I find the change in height of the mercury column for a temperature change of 35 degrees cecius if coefficient of volume expansion is 0.00018?
2007-11-30 13:33:29 · 2 answers · asked by glance 3 in Science & Mathematics ➔ Engineering
Calculate volume of mercury. Then multiply that by 0.00018 times 35 degrees.
2007-11-30 13:39:58 · answer #1 · answered by Tim C 7 · 1⤊ 0⤋
I think Tim C's right to work with change in volume
a^b means a to the power of b
I've put (some) units in square brackets eg [cm]
Calculations for initial state---
CSA tube [cm^2] = pi * (0.0018^2)
Volume in tube [cm^3] = height Hg in tube * CSA_tube
Volume in bulb [cm^3] = 4/3 pi (0.25^3)
Vbefore [cm^3] = Volume_in_tube + Volume_in_bulb
(Here there's a tiny bit of an over estimation. Look very closely at the intersection of "cylinder" and sphere. It's counted twice! The "Error" caused by this, probably hardly effects the end result, and is likely to be less significant than those introduced when measuring the lengths)
Calculations for final state---
Vafter [cm^3]=Vbefore*Delta_T * coefficient V. expansion
Delta_T=35 [deg C]
Vchange = Vafter-Vbefore
Height_after[cm] = Vchange[cm^3] /CSA_tube [cm^2]
2007-11-30 22:09:07 · answer #2 · answered by Steve C 6 · 1⤊ 0⤋