Some of the coolest rides at an amusement park whip you upside down loop by loop at heart-pounding speeds. How do you stay in your seat without falling out? And exactly what causes that strange floating feeling in your stomach when you zoom down the tracks of a roller coaster? This book explains how gravity helps make the best thrill rides even more thrilling. HI-LO/reading level grade 3, 32 pages each, full-color photographs, paperback. Save $1 per book when ordering 10 or more copies.