# Homework Help: Wind Resistance and/or Wind Accumulative Value

1. Dec 10, 2008

### Nighthawk1

1. The problem statement, all variables and given/known data

I'm working on a project and my physics is a bit weak as I haven't done physics since High School and I needed to figure out wind resistance when travelling in a car at various speeds. For example: If you are travelling down the Interstate at 65mph, how much wind resistance will you incur? And let's say that the current natural wind velocity in either direction is zero. For a better example: Let's say I have a hollowed cylinder mounted on the hood of my car and I am travelling at 65 mph. How much wind velocity will go through that cylinder? And let's say the cylinder's interior diameter is 5 inches.

2. Relevant equations

3. The attempt at a solution

2. Dec 10, 2008

### Carid

Wind resistance will depend a lot on the shape and size of your car. A Hummer H2 and a Porsche G2 will experience rather different amount of resistance.

As for that cylinder, if the shape presents some resistance to the flow of air (which it will) then the air which does manage to get inside will be at a lower pressure but a higher velocity. This is described in http://en.wikipedia.org/wiki/Bernoulli's_principle

Now why would someone want to put an open cylinder on his car hood?