How do balls bounce

As a consequence, the ball shoots up with less energy than it had when it reached Earth. Our planet, being so massive, does not move as a result of the collision. It is interesting to compare a heavy and a light ball as they fall from the same height. Both balls will fall at a similar speed, but because kinetic energy is proportional to the mass of the object, the heavy ball reaches Earth with more energy.

It will not necessarily rebound higher, as it also needs more kinetic energy to reach a specific height again. What if we could give the kinetic energy of the heavy ball to the lighter ball? When two balls collide, they exchange energy. Can we let one ball fly off with the energy of the other—and if so, how?

Do this activity to find out! Observations and results Did you find that a single ball never bounced back to the height at which you released it, regardless of the ball you used? As no energy is added to the ball, the ball bounces back with less kinetic energy and cannot reach quite the same height.

Had you given the ball an initial push, you would have added energy, and the ball might have bounced back higher. A well-inflated ball bounces better because it has more air inside. This allows it to push back faster, reducing the contact time and contact area in a collision and thus reducing the heat produced. Tennis balls also have air inside but they cannot be reinflated. Did you also see how a lighter ball shoots high into the air when released at the same time on top of a heavier ball?

Both balls fall at the same speed but the heavier ball gains more energy during the fall. When the lighter ball bounces on the heavy ball they exchange energy, and the lighter ball flies off with some of the energy of a heavier ball. It reaches way higher than from the height it was released. The heavy ball, on the other hand, is left behind with little energy and does not move much. This activity brought to you in partnership with Science Buddies.

Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. If polymers are tighter together, the ball bounces higher. Knowing this, you might be able to predict what the polymers are like in, say, a basketball, a ping pong ball, or a racquetball. But what about a steel ball? It has different polymers than a rubber ball. Believe it or not, a steel ball actually bounces higher than a rubber ball. When it hits the ground, the steel snaps back faster.

The steel is better at storing energy, which helps give it a lot of bounce power. You can investigate bounciness with an activity at home. Here are some instructions to make your very own bouncy ball. How high will your bouncy ball go? This stage begins the ball's journey back to where it began. Its velocity and acceleration vectors are pointing the same direction, meaning upward movement.

The ball is less deformed than the maximum deformation stage, and due to its elasticity, it is now pushing against the surface with a force greater than its own weight. This is what will cause the ball to bounce upward. At zero contact rebound, the ball is no longer deformed and is barely touching the surface, essentially only at one point. Velocity is moving the ball upward, but at this point, acceleration switches to oppose the velocity vector.

This is because there is no longer any force from the elasticity of the ball pushing on the surface, giving it an upward acceleration. Acceleration due to gravity, which pulls downward, will now be the only force acting on the ball in a perfect system. At full rebound, the ball has left the surface, and its velocity vector still points upward, though shrinking steadily due to the acceleration or deceleration due to gravity.

Following this step, the ball with reach peak at a new step, one where its velocity vector is zero, and the only force acting on it is gravity. The case of the bouncing ball above was simplified to remove any other forces like air resistance, imperfect elasticity, spin, friction, and the force from an initial throw, among others. All this means that bouncing ball physics gets more complicated from here.

When balls have any spin, as they usually do when thrown, and when the surface they hit isn't frictionless, the spin of the ball reverses from before to after impact. This is due to the force of friction.

When you drop a ball, gravity pulls it toward the floor. The ball gains energy of motion, known as kinetic energy. When the ball hits the floor and stops, that energy has to go somewhere. The energy goes into deforming the ball--from its original round shape to a squashed shape.

When the ball deforms, its molecules are stretched apart in some places and squeezed together in others. As they are pushed about, the molecules in the ball collide with and rub across each other.

Exactly what happens to these molecules as they stretch and squeeze depends on what the ball is made of. Suppose you drop a ball of putty. Rather than bouncing, it hits the floor and flattens. All of the organized motion of the falling ball becomes the random motion of jiggling molecules.

The random motion of jiggling molecules is a measure of thermal energy.