![]() ![]() When you drop a ball from a greater height, it has more kinetic energy just before it hits the floor and stores more energy during the bounce-it dents farther as it comes to a stop. It depends only on the elasticity of the ball itself-a super ball returns a large fraction while a beanbag returns a tiny fraction. Conveniently enough, this fraction of returned energy is nearly independent of how much energy the ball had to begin with. Thus a typical ball bounces to 60% of its original height because it stores and returns 60% of the energy it had before the bounce. That height fraction is equal to the fraction of energy that the ball successfully stored and returned during its bounce. The ball then rebounds: it undents and tosses itself up into the air to a good fraction of its original height. By the time the ball comes briefly to a stop, most of its missing energy has been stored in its dented surface. Because the ball is softer than the floor, it does most of the denting and stores most of the energy. This denting extracts energy from the ball’s motion and stores much of it in the elastic surfaces of the floor and ball. Because of these forces, both the ball and floor deform inward. It pushes downward on the floor and the floor pushes upward on it. By the time it reaches the floor, the ball is traveling quickly and it hits the floor hard. As it falls, the ball converts energy stored in the force of gravity-gravitational potential energy-into energy of motion-kinetic energy. The answer lies in how far the ball has dented inward due to its collision with the floor. At that instant, how does the ball “know” how high it should bounce? Something about its situation then must determine its rebound, but what? If you follow the motion of either ball, you’ll realize that there’s a moment halfway through its bounce when the ball is perfectly motionless in contact with the floor. ![]() Why if you drop a ball from say 2 meters does it bounce higher than a ball dropped from 1 meter? ![]() ![]() However, they only stretch for an instant before atomic interaction forces them back into their original, tangled shape and the ball shoots upward. These polymers are tangled together and stretch upon impact. On a molecular level, the rubber is made from long chains of polymers. The ball pushes on the floor and the floor pushes back on the ball, causing it to rebound. This is Newton’s Third Law of Motion- for every action there is an equal and opposite reaction. If the ball is elastic in nature, the ball will quickly return to its original form and spring up from the floor. When the ball collides with the floor, the ball becomes deformed. The total energy of the system remains the same the potential energy changes to kinetic energy, but no energy is lost. Both potential and kinetic energy have units of Joules (J).Īs the ball falls through the air, the Law of Conservation of Energy is in effect and states that energy is neither gained nor lost, only transferred from one form to another. The formula for kinetic energy is KE=1/2 mv 2, where m is the mass in kg and v is the velocity in m/sec 2. As the ball falls through the air, the potential energy changes to kinetic energy. The formula for gravitational potential energy is PE = mgh where m is the mass of the ball measured in kg, g is the gravitational acceleration constant of 9.8 m/se c2, and h is the height of the ball in m. Potential energy is the energy of position, and it depends on the mass of the ball and its height above the surface. When you hold a ball above a surface, the ball has potential energy. Everyone has played with balls that bounce, but few people truly understand the physics behind a bouncing ball. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |