Buildling A Rubber Band Car Teresa Glass

Author(s)Teresa Glass Arleta High School

NGSS Engineering Standards

Practice 2 Developing and Using Models Modeling can begin in the earliest grades, with students’ models progressing from concrete “pictures” and/or physical scale models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system. (NRC Framework, 2012, p. 58) Models include diagrams, physical replicas, mathematical representations, analogies, and computer simulations. Although models do not correspond exactly to the real world, they bring certain features into focus while obscuring others. All models contain approximations and assumptions that limit the range of validity and predictive power, so it is important for students to recognize their limitations.

Practice 6 Constructing Explanations and Designing Solutions The goal of science is to construct explanations for the causes of phenomena. Students are expected to construct their own explanations, as well as apply standard explanations they learn about from their teachers or reading. The Framework states the following about explanation: “The goal of science is the construction of theories that provide explanatory accounts of the world. A theory becomes accepted when it has multiple lines of empirical evidence and greater explanatory power of phenomena than previous theories.”(NRC Framework, 2012, p. 52) An explanation includes a claim that relates how a variable or variables relate to another variable or a set of variables. A claim is often made in response to a question and in the process of answering the question, scientists often design investigations to generate data. The goal of engineering is to solve problems.

Materials needed

Connector Strip, dowels, Hole Plate, wheel Hub, Stretch tire, Rubber Band, tin machine Screw, Nut, slide(100mm), stop clip, 50 tooth gear, 40 tooth gear , 20 tooth gear, 10 tooth gear ,string, cutter , reamer, wax, hammer, pliers, screwdriver.

Procedure

Provide a step by step procedure that explains the engineering activity

The whole objective of this activity is to build, race and reengineer a rubber band powered vechicle , while applying the science concepts of energy, simple machines, and friction.

1.Start building the racer by assembling the frame first. Cut four 100 mm dowels. Insert them into two hole plates. Wax the dowel ends. do not ream any holes especially holes which dowels should be placed into.

2. Work on the wheels next. Cut two 125 mm dowels. They will become axles. Insert them into the two wheels.

3. Place the wheel 7 axles from step 2 into the frame. Move them around to place them where you think they will function best. Press the two remaining sheets into the axles. Make sure that the wheels are not tight against the frame. Do not ream.

4.Let it roll. roll your racer across the floor or down a ramp. Reduce friction allowing it to roll the furthest possible distance.

5. Add traction. Rubber tires can be stretched around your wheels to provide traction. applying glue to the outside of the whee will help the stretch tire stay on after the glue dries.

6. Attach two #16 rubber bands to one stop clip. Place the stop clip on the wheel axle next to the stretch tires. Attach the stop clip so the hook is facing away from the racer when up. Rubber bands can be attached by either method by winding them or knotting them.

7.Secure the clip. The stop clip may slip(rotate on the axle) when pulled by a rubber band. This can be prevented with a drop of glue. You may invent your own way to hook the rubber band.

8. wind up your rubber band racer. Hook the rubber band around the clip. Wind the rubber band around the axle by pulling the racer backwards with wheels on the ground, or by holding the racer and turning the wheels backward with your hands. Let it go!!!

Questions

• 1. Describe mechanical advantage and explain how it works. Mechanical advantage is the relationship between the input force (work in ) and output force (work out) work equals force times distance. The distance over which the input force is applied equals the distance which the output force is applied. for example the force released by a rubber band contracting over a distance converts to the force of the racer and the distance it travels.

• 2.What happens to the force in your racer if you connect the rubber band in a series? rubber bands in series release less force over a greater distance.

• 3. How can a lever arm create a mechanical advantage on your racer? A lever arm and string can create a mechanical advantage between the rubber bands and the driven wheel to increase the distance traveled or the vehicle speed.

Photos

• Photos of Engineering Project

Movies

Include movies that you have taken. Your movies should be placed in your youtube account.

References

http://teachergeek.com/http://teachergeek.com/