Jul 6, 2017
7
1
Status
Pre-Optometry
Hey guys, I was doing the questions in the physics portion, specifically thermodynamics, in the Kaplan book 2017-2018. I had a look at questions, and questions 3 is asking about change in length of a rod. The alpha coefficient they used is in Kelvin but the temperature they used is in Celcius... In my head, the units should cancel out so that only meters is left for the answer? Or am I wrong about this? [The equation is L=(alpha)(L)(change in Temp)]. I'm not good at physics, nor have I taken the course, so I'm not too sure if it was a mistake or not. Thanks!
 

pnw256

2+ Year Member
Feb 24, 2015
63
33
Status
Pre-Optometry
Hey guys, I was doing the questions in the physics portion, specifically thermodynamics, in the Kaplan book 2017-2018. I had a look at questions, and questions 3 is asking about change in length of a rod. The alpha coefficient they used is in Kelvin but the temperature they used is in Celcius... In my head, the units should cancel out so that only meters is left for the answer? Or am I wrong about this? [The equation is L=(alpha)(L)(change in Temp)]. I'm not good at physics, nor have I taken the course, so I'm not too sure if it was a mistake or not. Thanks!
In this case, it doesn't matter if it's C or K since it's delta, or change of, T. If you recall, 1 degree of Celsius change is equal to 1 degree of Kelvin change; the only difference is that 0 K is absolute zero and 0 C is equal to 273K. Now if you're plugging in T for a PV=nRT problem, it'll be important to use K in this case since the gas constant is based on Kelvin and T, in this case, is referring to the temp at a specific point in time and there's no change.