You are here:

Physics/Thermodynamics

Advertisement


Question
We say black color is a good absorber of heat.
Then why is it that we apply black sheets on our car windows to protect from the sun's glare.
Why doesn't it increase the car's temperature whereas a black cloth worn makes us sweaty.

Answer
We don't, we apply reflective shields if that is our goal.  Though if you apply tinting to the outside, half the heat will be re-radiated outside, so that will help.  Otherwise the light comes through and gets mostly absorbed in the car's dark interior.  The problem with black clothes is that they absorb light completely, but light clothes reflect a large fraction of it entirely.  That means that half the heat of the sun is re-radiated inside both on the way in and back out for black clothes...but for light clothes you might reflect a large fraction of the Sun's light entirely...then it comes down to clothing design and convection to cool us.

Physics

All Answers


Answers by Expert:


Ask Experts

Volunteer


Dr. Stephen O. Nelson

Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

©2016 About.com. All rights reserved.