# Gettin’ Real with Centripetal

Check out this dangerous curve near downtown Atlanta (click the picture to embiggen — it’s the loop in the lower right corner). The curve I’m looking at takes traffic toward the southeast, around the curve with all the perfectly placed trees. Drivers have to navigate a really tight turn. Plenty of them don’t believe the signs warning them to slow down to 25 mph.

How fast can you go around that turn safely?

Georgia Performance Standards: SP1g

SP1. Students will analyze the relationships between force, mass, gravity, and the motion of objects. g. Measure and calculate centripetal force.

## 3 thoughts on “Gettin’ Real with Centripetal”

1. suevanhattum

How did they determine when a car would start slipping?

• How’s your physics? It involves static friction and the radius of the curve. I gave them a reasonable value for the coefficient of static friction for a “typical” car tire. (Don’t want to give it all away here because my students will totally Google for a solution. Won’t give them the satisfaction!).

Drop me an email if you want to see a full solution. It’s mgolding “at” the gmail.

2. suevanhattum

I figured it out when I took physics long, long ago. I suppose I could figure it out again. Google says .7 (for the coefficient of static friction for a “typical” car tire). Is that good?