You feel the wind rushing in your face.

You are hanging upside down! 

Millions of kids and adults take these thrill rides each year. 

Some experts worry that the rides' sudden twists and turns are unsafe

High-speed coasters whip riders' heads back and forth.

One report blamed coasters for 13 brain injuries from 1995 to 2000. 

Another report says some people have nearly died from coaster-related brain injuries.

Recently, two scientists have set out to learn if coasters really do cause brain injuries.

They studied the effects of riding three of the fastest coasters in the United States.

The scientists say the coasters' twists and turns are not fast enough to cause brain injuries.

People take more than 1 billion rides on roller coasters each year.

They want a new study.

He has asked a group of experts to include children in their next study about roller coaster safety.  

Results from that study will be reported next year.

 Roller coasters have to be studied

The idea for the roller coaster began with the ice slide. 

 It speeds down a track at more than 100 miles per hour.