After carefully designing our protection systems to reduce energy transfer and ultimately peak forces, we set out to do some testing!  We agreed on a drop height for our phone cases, and our water balloon launcher didn't work as well as we thought to mimic a bike crash, so we reverted to Mrs. Brinza throwing them against a brick wall.  So many groups were successful in their designs!  Looks like we got some future engineers on our hands here at LMS!

We then turned to the DQB to answer questions that launched our unit together.  We've figured out so much about energy transfer, peak forces, deformation, and engineering solutions to problems involving collisions.  We had a great year together 6th grade!  I am so proud of how much you figured out!

Throughout our unit, we've been figuring out so much about energy transfer, peak forces, and reducing peak forces that we decided to put all our new found ideas into action by redesigning one of the following:

1.  A better phone case, using sugar class as the "phone."
2.  A better bike helmet, using a water balloon as the "brain," which is affected if a concussion happens.

Students had so many ideas!  Up next--test our protection systems!

With our understanding of forces and energy transfer at an all time high, we came up with a list of criteria and constraints to consider not just for a phone case (which launched our unit), but for any system that's designed to protect something of value to us.

We agreed that materials that seem to be top performers share one big idea in common:  There's lots of empty space in them--like in bubble wrap.  This makes it harder for the energy to transfer, as it can only transfer when two objects come in contact!

So how can we use this to answer our questions that were a part of our launch about protecting things of value to us?

We are seeing through all these investigations that the surface impacts the amount of energy transfer.  Bumpier surfaces allow more energy to transfer to them.  When energy is transferred to a surface because two object rub against each other, this is friction!  And when energy transfers to the air because the object transfers energy to the molecules/particles in the air, this is air resistance.

We're feeling fairly confident that if we change various variables to increase air resistance and slow energy transfer in a system, we can possibly reduce peak forces and prevent damage.  But which materials would work best to do this?  Why do some materials work better than others?

It's clear that when there's more speed or mass in a collision that there is more energy in the system.  We're not sure, however, which makes more of an impact--speed or mass.  So we set up our investigations again, this time slamming our carts into something fragile--a saltine cracker!  We then compared the qualitative results, and it was obvious!

We then realized that while our qualitative results were helpful, we needed some quantitative data, too!  Using a simulator , students recorded data were both speed and mass were changed accordingly.  We graphed the data the class collected to create two comparable situations:

With lots of thoughtful discussion, students came to the following conclusion:

1.  While both mass and speed increase the energy in a system, speed seems to make more of an impact.

2.  If you double the mass in a system, the kinetic energy doubles.  If you triple the mass in a system, the KE triples.  It's like a 1-1 situation!
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3.  If you double the speed in a system, it makes more than double the KE in a system.  In fact, it's quadrupled!  And if you triple the speed, the KE ends up being 9x the original!

With our consensus model updated, we revisited what we've figured out in terms of cause-effect relationships!

1.  Increasing the speed or mass of an object in a collision increases the amount of kinetic energy in the system.

2.  If there is more KE in a system, then the peak forces will be higher.

3.  And if there are higher peak forces, there will be more deformation in the objects, and potentially more damage!

We are honing in on our understanding of how to represent this, by taking some guided notes with free-body diagrams!