by Karen Rogers

Created on: September 08, 2008

Take one fast sprinter with a pole, add in gravitational potential energy converted to kinetic energy, and you have the physics for a successful pole vault!

Kinetic energy is the energy of motion. All moving objects, including the wind, roller coasters or our sprinting pole vaulter, have kinetic energy. The faster an object or a person moves, the more kinetic energy it has. This explains why a car hitting a wall at 5 miles per hour will just dent the bumper, but when it hits a wall at 40 miles an hour, the car is totaled. The greater (faster) the motion, the more kinetic energy an object has.

Next comes gravitational potential energy, or the energy due an object's position or place. It's the energy stored in an object as a result of its height or vertical position and the force of gravity. There is a direct relationship between height and gravitational potential energy: the taller or higher an object, the greater the gravitational potential energy. Since gravitational potential energy is directly proportionate to its height, doubling the height will also double an object's gravitational potential energy. A roller coaster car sitting motionless before a 100-foot drop has double the gravitational potential energy of a roller coaster car with at a 50-foot drop.

Here's an example of kinetic energy and gravitational potential energy acting on an object. You just placed a book on a low table. The unmoving book has gravitational potential energy. You can release this gravitational potential energy by knocking the book off the table. As the book falls, its gravitational potential energy is converted into kinetic (motion) energy. When the book hits the floor, all motion stops and the kinetic energy is converted into heat and sound upon impact. This time, however, place the book on top of a table or shelf 3 times higher to increase the gravitational potential energy 3 fold. Now knock it off. Since the book is falling from a height 3 times greater than the low shelf, the book has more time to build greater kinetic energy and will hit the floor with a much louder sound and greater impact. Increased height means increased gravitational potential energy and greater (faster) kinetic energy. This also explains why a roller coaster having a hundred foot drop is a lot more exciting than one with only a fifty foot drop!

Our pole vaulter is going to be tall and lean to achieve the maximum gravitational potential energy and kinetic energy. A tall sprinter can hold the pole higher to

• 1
• 2
• Next Page >>