Objective

By the end of this lesson, you will be able to understand the physics principles involved in building a BMX bike and apply them to create your own design.

Materials and Prep

• Pen and paper
• Ruler or measuring tape
• Access to the internet or books for research

Prior knowledge of basic physics concepts such as force, motion, and energy will be helpful for this lesson.

Activities

1. Research and Design: Use the internet or books to research the different components of a BMX bike. Take notes on the different parts and their functions.
2. Calculating Gear Ratios: Use your ruler or measuring tape to measure the diameter of the front and rear gears. Calculate the gear ratio by dividing the number of teeth on the front gear by the number of teeth on the rear gear.
3. Understanding Forces: Identify and explain the different forces acting on a BMX bike while in motion. Discuss the role of gravity, friction, and air resistance.
4. Energy and Momentum: Explore how energy and momentum are transferred and conserved in a BMX bike. Discuss the relationship between potential energy, kinetic energy, and momentum.
5. Experiment with Balance: Use your knowledge of physics to experiment with different frame designs and weight distributions to achieve optimal balance and stability for a BMX bike.
6. Present Your Design: Create a visual representation or a written report showcasing your BMX bike design, explaining the physics principles applied, and presenting your findings.

Ninth Grade Talking Points

• "In order to understand the physics behind building a BMX bike, let's start by researching the different components of a bike and their functions."
• "Gear ratios play a crucial role in determining the speed and power of a bike. Let's calculate the gear ratio of a BMX bike using the number of teeth on the front and rear gears."
• "Forces such as gravity, friction, and air resistance affect the motion of a BMX bike. Let's discuss how these forces come into play."
• "Energy and momentum are important concepts when it comes to understanding the movement of a BMX bike. Let's explore how these concepts apply to our design."
• "To achieve optimal balance and stability, we can experiment with different frame designs and weight distributions. Let's test out various configurations and observe the effects."
• "Finally, let's showcase our BMX bike design by creating a visual representation or a written report. Make sure to explain the physics principles applied and present your findings."