When a Ball Bounces

To look at a ball bouncing you may think this is a really simple task. The ball moves down and then moves up when it hits something for a while and starts the process again until it stops. There is a lot more going on than you may think, being able to slow time down allows us to examine what is really happening.

The Beginning

To start with the ball must start to fall towards the floor, this is our first force called Gravity. Gravity changes depending on the mass your on (i.e planet earth). For instance the moon, gravity is lighter but we won't go into that too much now. All we really need to know about gravity on Earth is that an object will accelerate by 9.81 meters per second. This means for every second, an object will increase its downwards speed by 9.81m/s. The higher the ball the higher the speed it will hit the ground. An example would be if you have a car that did 0-60mph in 10 Seconds and you accelerated as a constant speed you acceleration would be 6 mph/s. Lets say once you get to 60mph you want to hold you speed you need to stop accelerating so the new acceleration would be 0 mph/s.

Free Fall

There is a maximum speed call the Terminal Velocity. All this loosely means is imagine an object that wants to move down into the empty space below it. We may see it as empty space but that space is filled with the air we breath. This air needs to be moved out of the way before the object can occupy that space and the space left behind it needs to be refilled with the air. We cannot just pick it up and move it through the object so the air has to move around the surface of the object in an orderly fashion, this movement is called Air Resistance. This could just as easily be Water Resistance of what ever substance surrounding the ball is engulfed in, it's just the strength or resistance of the substance that changes. The fact there is a resistance means we have a slowing force so it cannot keep speeding up forever. At some point it cannot go any faster and this is the Terminal Velocity.

Make an Impact

The ball starts the bounce process, this is the moment adhesion with another object happens. Please note we call this adhesion not cohesion as it is assumed that we are dealing with different materials or similar materials that is not capable of combining to make a single object. While adhesion is taking place, the ball started to compress, this starts storing the energy from the impact and the spin energy of the ball which it will release later on. This ball increase its surface area and in turn increases the adhesion.

Slippery Slope

This adhesion will be over come as the compression force is absorbed and turn transitioning into a sliding action. When the pressure exceed the static friction for the adhesive area. As the ball starts to slide. Kinetic friction is now at play beginning to slow the ball. When the ball fails to move faster that the Kinetic Friction the Slide stops and adhesion with the surface starts again.

On a Roll

The momentum in the ball is still pushing forwards so the only other option is for the ball to start rolling and this is the only other action left. As the ball starts rolling it is at this point the ball starts to release the energy.

Let it All Out

This energy creates an upwards lift and increases the rotation of the ball up until the point the ball has full release all of its energy.

On the Up

The final action is a slowing action where is need to break the adhesion but as the footprint is so low this is nominal and the ball starts being effected by gravity and air resistance again to slow it down. This time the air resistance work with gravity to slow down the ball to nothing.

Lets do That Again

This now starts to repeat the above process until it stops moving.
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