The Beginning: Downhill

It's a safe bet that as you begin you flight down the hill your not thinking to yourself, "I wonder what is actually happening to me as I sled down this hill." But what does go on when you are moving down the hill? The simple answer is gravityGravity and normal forces are the first two basic forces acting upon you. Gravity pushes against you towards the hill, while the normal forces act in the opposite direction. With these two forces acting in opposition of each other, they would appear to cancel each other out, but then why do you still move down hill? The answer lays in the hill itself. It is because of the sloped surface of the hill that you move. In a perfectly horizontal hill, your net force would be zero, and on a perfectly vertical hill you would have a net force equal to your weight.

The diagram to the left shows the resulting forces and how gravity pulls you down the hill. Since the vertical forces of gravity are canceled by the normal force. There is still the horizontal effect of gravity's pull. Giving you a force which is equal to your mass times the acceleration due to gravity times the sine of the angle of the hill.

If you keep increasing speed as you go down the hill then why do you slow down once you reach the bottom? Since you are no longer going down an incline the normal forces and forces of gravity cancel each other out. Your velocity will be the same as when you left the bottom of the hill due to inertia. The only reason you slow down is becuase of wind resistance, which we have ignored for simplicity sake, and friction which will be explained inthe next section.

Opening Page

Forces of Friction

Loop-the-Loop

Glossary of Terms

Bibliography