Newton said that for every action there is an equal and opposite reaction.  Collisions are the thing that happens when two objects slam into each other!  But what does that mean for science?  Well, depending on the object’s material(such as using silly putty vs using marbles, skee balls, or shots), mass, and vector (magnitude and direction) it can mean a few things.  There are two different types of collisions that we can witness on a daily basis.  Inelastic and elastic collisions.  An inelastic collision is a collision that has a conservation of momentum, but not kinetic energy.  Whereas an elastic collision conserves both kinetic energy and momentum.  There are different types of energies.  Kinetic energy can be thought of as “moving” energy.  There is also potential energy, rotational, thermal, gravitational, chemical…the list goes on.  


Momentum is defined as the strength or force that something has when it is moving. Most ordinary collisions that you witness are considered inelastic because of the sounds you hear (sound=type of energy -> total kinetic energy – sound =loss of kinetic energy), or the heat released (same as above)..  The most elastic-like collision is when two billiard balls collide (or like in our experiment)  they are technically inelastic collisions because the loss of energy in the sound, but that energy is negligible (meaning that it doesn’t matter a whole lot).



To play around with different outcomes of mostly elastic collisions you can change a few variables such as mass, density, and velocity (speed and direction).  We used some similar sized objects, and then some extremely different sized objects to test this out.  We also changed the angle of impact to see where the different objects would end up after impact.  It turns out that a slight angle change makes a big difference due to the curvature of the balls.  This is something that professional billiards players have to take into account at every shot.  The speed of the objects just before impact makes a huge difference also. If you try to collide the two objects with a slow enough velocity then the objects may just travel together.  On the other hand if you slam them into each other you might see that there is a nearly complete transfer of the kinetic energy from the first object to the second.   


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