- #1

spsch

- 111

- 21

- Homework Statement
- A hair dryer blows air at 10 Liters per second, the air is heated with a 1000 W heater while the air is measured at 960 mbar and 20 Degrees Celsius. What is the Temperature of the air when it is leaving the hair dryer.

- Relevant Equations
- KE = 3/2kT

Hi, so I found this on another old "AP" High School Finals Exam.

I think I may be super lost.

Because the only way that I can think about is KE = 3/2kT. And then that the difference of the Kinetic Energy of the air Particles is the Q supplied by the heater inside the air dryer.

So ## \frac {3}{2}k*(T_1 - T_2) = 1000 W ## then ##T_2 = T_1 -\frac {2}{3k}*1000 ##

Or with ## Q = mc(T_1 - T_2) ## but we'd need a table for c and the density of air then. Which are then usually supplied.

I think this is wrong because I am also given the Pressure and Volume and I wouldn't need it then. But I have been wrecking my brain about for a bit and I can't figure out where. I'm so sorry.

Thank you for any pointers that could help push me in the right direction.

I think I may be super lost.

Because the only way that I can think about is KE = 3/2kT. And then that the difference of the Kinetic Energy of the air Particles is the Q supplied by the heater inside the air dryer.

So ## \frac {3}{2}k*(T_1 - T_2) = 1000 W ## then ##T_2 = T_1 -\frac {2}{3k}*1000 ##

Or with ## Q = mc(T_1 - T_2) ## but we'd need a table for c and the density of air then. Which are then usually supplied.

I think this is wrong because I am also given the Pressure and Volume and I wouldn't need it then. But I have been wrecking my brain about for a bit and I can't figure out where. I'm so sorry.

Thank you for any pointers that could help push me in the right direction.