POTSDAM -- The North Country Children's Museum presents “Roller Coaster Physics" on Saturday, March 8 at the Clarkson Bookstore, 39 Market St. MotionCraft Technologies invites children in kindergarten through fifth grade to participate from 12:30 to 2 p.m. to explore the science of roller coasters through a series of fun and challenging toy car activities. Toy cars will be given to the children and they will investigate how their car behaves on magnetically wall-mounted adjustable tracks. By observing what makes their car go faster, higher, and further, the children will be able to figure out what their car will do on a set of challenge tracks. These contests include hitting a target, stopping on a cliff, negotiating a loop, and jumping through hoops.