Step 1: Research

• Use the information below to do some research about bobsleds. You may choose to read this as a whole class, or have the students pick groups first, read it, and then discuss it as a class.
• Regardless of the method, when reading is done, make sure to hit on key points. (i.e. what forces make the bobsled go. How can you make your bobsled faster? what sorts of things will make a bobsled slower?)

About Bobsledding

If you've ever hit a patch of ice while driving your car, you've experienced a very tiny piece of what driving a bobsled is like. On an icy road, there's almost no friction between your tires and the road surface, so you can't steer very well. And any sudden moves, like hitting the brake, can send you spinning out of control.

So imagine if your car was open at the top and back — like a bobsled — and that the patch of ice lasted for almost a mile. Not a mile of straight, level road, either — a mile that's downhill and full of dramatic curves. That's what being in a bobsled is like. Drivers and crew slide down a hill on a track, or run, that's full of twists and turns. A wrong move can cause a dramatic crash.

The International Bobsleigh & Skeleton Federation (IBSF) sets rules for the composition and dimensions of each of these components, as well as the total weight of bobsleds. Bobsled manufacturers work closely with bobsled teams and designers to make the best sled design.

Each type of bob has a minimum weight when empty and a maximum weight with bobsledders and their equipment.

Heavier sleds go faster, so teams that do not reach the maximum occupied weight may add ballasts to make their bob heavier. Officials weigh the sleds at the end of the run to make sure they meet the weight requirement.

Bobsledders begin the race in a push-off stretch. This is a straight stretch that's wide enough to allow the bobsledders to push the bob. The athletes have to run as fast as they can — this push and gravity are the bob's only sources of speed for the entire race.

But winning a bobsled race starts long before the push-off stretch — it starts with the design of a fast, efficient bobsled. A good bobsled has to take advantage of the physical forces that help it accelerate, and it has to minimize the forces that slow it down.

Acceleration due to gravity is the same for all of the bobsleds in the race — it's the physical constant of 9.8 meters per second squared. Drag, friction and momentum, on the other hand, all vary based on bobsled design and can affect how much the bob actually accelerates. The strongest, fastest, most skilled team in the world cannot compensate for a bob design that ignores these factors:

• Drag: Air passing around the bobsled creates drag, which slows the bobsled down. Wind tunnels and computer simulations help teams design bobsleds that are as aerodynamic as possible, cutting down on drag and helping the bobsled go faster.
• Friction: There's not much friction between smooth metal and ice, but even a tiny amount will slow the bob down. For this reason, fast bobsleds have very smooth runners that are as thin as possible while still meeting IBSF requirements. Each bob's runners scrape and scar the ice on the way down, so teams that race later in the day have more friction to overcome.
• Momentum: An object's momentum is its mass times its velocity. The more massive an object is and the faster it goes, the more momentum it has. The more momentum it has, the harder it is to stop. So, bobsleds with lots of momentum can more easily overcome the affects of drag and friction. A team that combines a good push-off with a bob that is very close to the maximum allowed weight has an advantage for the rest of the race.

After the push-off, gravity and momentum take over, accelerating the bobsled downhill. The driver has to choose a path down the run very carefully. Steering too high on a curve adds to the total distance the bob has to travel, making the trip take more time. A driver who steers too low loses the advantage of centrifugal force that keeps the bob going during banked curves.

In the end, all of these physical forces and athletes' actions lead to a very tight race. Often, the winning team's time is only a few hundredths of a second faster than that of the second-place team.

All information taken from https://adventure.howstuffworks.com/outdoor-activities/snow-sports/curling.htm

Step 4: Building/testing/rebuilding

Note: this may take more than 1 day to complete.

• Most of the Fun Fridays in November and December will be spent, building, testing, and rebuilding your design to achieve maximum results. This is a difficult project. Be a critical thinker and use some creativity to find solutions to problems you encounter.
• Each group may sign up for a time slot to test their product. If there is any inappropriate behavior in the hallway, it will result in an automatic Think Time